There are already some good ideas out there for GMs looking to recruit people for a campaign, like the Recruiting Office Rules and Coboney's blog entry about Advertising for a Game. Many GMs seem to be taking these into account pretty well. The Reputation System is sometimes not effective, though, when many of the players applying to a campaign are relatively new Users, so I wanted to share my ideas here about good recruiting strategies that will, by extension, help to ensure you have a good game. I've developed these mainly with PbP games in mind. The tips here are targeted at the GM doing the recruitment, but they are just as important for players to read and keep in mind when making their applications as well.
1. Set a date for the end of recruitment. Say how long you'll be recruiting for. Continue accepting applications for that full time. I've seen TONS of games just say "looking for 5 people" and then end recruitment when 5 people have expressed interest. Some people don't even wait until those 5 interested people have completed a character sheet. I don't personally follow up and check on those games, but based on my own experiences, that doesn't bode well for the game lasting very long. I see so many people express interest in recruitment threads that never follow through with a sheet - they just disappear. As for how long to recruit for, I'd say between 1 and 2 weeks. Any less than that and you might as well be saying "first come first served," and your players don't have a chance to come up with a character idea that would really mesh with your game then put that onto a character sheet. Any longer and you run the risk of the people who've already applied losing interest or patience, and you're probably running low on applicants by then anyway.
2. Pay attention to how well your applicants follow directions. If your applicants don't bother to read your recruitment post thoroughly, or can't follow through on all your directions at one try, it probably means you're going to constantly have to remind them of things, slowing the pace way down. For example, if you've set a date for your recruitment to end, be willing to accept applications just before and even just after the deadline, but be wary of those players - it might mean that they'll be the ones holding your game up for days every time they need to post. Many games have a recommended or required rate of posting (like once per day, or every other day), but let's be honest that we, or at least I (I can't necessarily speak for others, but assume that I'm not totally alone in this), would rather not kick people out for not meeting posting requirements if they're still around and posting from time to time, even if it means the game slows down more than we want it to. It's better to anticipate this sort of behavior before you even accept their application.
[Side Note: In a PbP game, which almost by nature goes so slowly, even the best player can forget what's happened... I like to make some sort of campaign log that is accessible to the players. Maybe a thread in your forum, or a sub-forum, or a shared Google Doc. You can keep it updated, or allow them to help in whatever capacity you're ok with, and you can always refer them back to it if they forget something campaign-related.]
3. Check how engaged in the recruitment process applicants are. I know it can be tough to gauge this, but it's helpful when you can. If an applicant's one and only post is their application, and they slide it in just before the deadline after recruitment has been going on for 2 weeks, it doesn't bode well for them checking in on your game. On the other hand, if they want to work with you to develop a character that really fits into your game, and there's a lot of back and forth between you, they're likely to stick around. Again, don't necessarily rule people out if they only post once or twice, especially if those posts are jam-packed with all of the other things you're keeping an eye out for (like following all the directions, making a good character, meeting the deadline, etc.).
4. Require a completed sheet, and check it. If you're running a game that requires character sheets (which is most games), this is important. It's not quite as important for games that don't have formal character sheets, but there's still probably something you need from them, and you should check it over. If they can't get around to making a sheet by the end of recruitment, they're not going to get around to much of anything else. Sometimes, they will submit an incomplete and/or incorrect sheet. It's important to check over the sheet and make sure they've got everything up to your standards. It's up to you how many T's need to be crossed and I's dotted, but make sure that they meet your requirements. Don't hold it against them for not following directions if you're not super-clear about what needs to be complete on their sheet, but you should expect the basics. I run D&D 5e games, so for me that means checking ability scores and mods, proficiency bonuses, items, attack and damage rolls, initiatives, character personality stuff, feats, spells, etc. (I also generally require at least an attempt at some sort of character biography, though I'm not strict about how detailed it has to be.) These things are virtually essential for a character to function properly, so it's important for the player to have them completed and correct. It's up to you if you're willing to work with players who are new and don't know, but I would encourage you to do so - everyone has to learn somehow, and people learn different ways. It's also up to your best judgment how much to dock an applicant (in terms of following directions) who takes a lot of back and forth to get everything complete and correct, but be patient and continue working with them until their sheet is done or recruitment is over. (This also helps you see how quickly they respond to your posts, giving you an idea of how often they'll post and building their engagement in the game).
5. Consider your applicants' experience. It's certainly ok to understand this to be their experience with RPGs or even your particular game system, but I'm referring here to their experience with PbP and the Tangled Web. The Recruiting Office Rules mention this, but I'm going to add to it. I typically try to get at least one player who's been around for a while to serve as a sort of anchor and unofficial helper at bringing newbies into the fold, and I also try to get at least one player who's relatively new so that they can get into a game. It's a toss-up for the rest of my players. You might try to keep it balanced with roughly 1 new(ish) to 1 veteran player, but it's really up to you. If the newbies drop out, you're still left with a few veteran players to continue on, and you can recruit a few fresh faces rather than having to end the game and/or start from scratch.
6. Keep an up-to-date list of completed applications in the first post of your recruitment thread. This is helpful for a number of reasons. The applicants can see if they're done, or if you need something else from them. Don't neglect to actually respond to their posts and provide information to them about what you need from them (after checking their character sheets, or for any other reason), but the list provides a constant and easy-to find reference for them. It also helps players who haven't applied yet to know if there's a glut of one type of character being submitted, in which case they might decide to submit a different type of character and increase their odds of getting selected.This helps you to balance the characters in your game, as I mention below. I typically include the applicant's character's race, class, and a link to their character sheet.
7. Look for the best fit in terms of player personality. Think about how they have communicated with you and with others. Were they helpful, sarcastic, to-the-point, or what? How did this make you feel about them? How did it seem to make the other applicants feel about them? Assume that they're going to act that way forever. Would having them in your game make it fun, or would it make it a drag and stress you out? You know what to do here.
8. Look for the best fit in terms of character personality. If you have an applicant who wants to play as a high elf paladin of Corellon with a special mission to exterminate all drow, and an applicant who wants to play as a drow, things are probably going to be difficult. Sometimes contrasts and conflicts create interesting, character-building moments. Sometimes they force players to compromise their vision for their character for the sake of the game, resulting in hurt feelings. Sometimes the player is unwilling to compromise their vision and force you as the DM to make it work or else break the game. Think about how significant these conflicts would likely be in your game, and, if you're really interested in both characters, be ready to either re-do some things or work with the players to slightly re-do their characters. Otherwise, only select one of the conflicting characters.
9. Look for the best fit in terms of character balance. Unless you have a special vision for a game of only one type of character (like all barbarians), your game will probably benefit from a well-rounded group of characters. It may not be possible to cover every base with the number of characters you're taking for a group (and maybe you shouldn't try to cover every base - let the characters figure out how to adapt to and account for their weaknesses), but try not to pick characters so that they have a lot of overlapping strengths and weaknesses. Often, applicants will notice a specific gap in character applications (if you're doing #6) and help you out in this regard.
10. Look for the best fit in terms of your game. Which characters spark your imagination? Which ones seem like they were born in your world and lived in it their whole lives? Which ones have a rich backstory that doesn't conflict with the core fundamentals of your game? These characters inspire you, which will help you make your game better, which will help keep your players around and engaged. Be open to work with players on their characters in this regard. Some will seek this sort of interaction (which scores them points for engaging in the recruitment, as mentioned in #3), but don't be afraid to bring it up to them even if they don't. See how they react to your ideas (and how quickly they respond). If they're open to them and seem excited about them, they're now more invested in your game. If they get upset about you suggesting changes to their character, they are inflexible and probably will derail your game to create the game/story they want for their character.
These ideas are not listed in order of importance, and it's your call which ones are more important to you and your game, but hopefully they give some insight that will help you select a good batch of players and have a fun, long-lasting game.
1. Set a date for the end of recruitment. Say how long you'll be recruiting for. Continue accepting applications for that full time. I've seen TONS of games just say "looking for 5 people" and then end recruitment when 5 people have expressed interest. Some people don't even wait until those 5 interested people have completed a character sheet. I don't personally follow up and check on those games, but based on my own experiences, that doesn't bode well for the game lasting very long. I see so many people express interest in recruitment threads that never follow through with a sheet - they just disappear. As for how long to recruit for, I'd say between 1 and 2 weeks. Any less than that and you might as well be saying "first come first served," and your players don't have a chance to come up with a character idea that would really mesh with your game then put that onto a character sheet. Any longer and you run the risk of the people who've already applied losing interest or patience, and you're probably running low on applicants by then anyway.
2. Pay attention to how well your applicants follow directions. If your applicants don't bother to read your recruitment post thoroughly, or can't follow through on all your directions at one try, it probably means you're going to constantly have to remind them of things, slowing the pace way down. For example, if you've set a date for your recruitment to end, be willing to accept applications just before and even just after the deadline, but be wary of those players - it might mean that they'll be the ones holding your game up for days every time they need to post. Many games have a recommended or required rate of posting (like once per day, or every other day), but let's be honest that we, or at least I (I can't necessarily speak for others, but assume that I'm not totally alone in this), would rather not kick people out for not meeting posting requirements if they're still around and posting from time to time, even if it means the game slows down more than we want it to. It's better to anticipate this sort of behavior before you even accept their application.
[Side Note: In a PbP game, which almost by nature goes so slowly, even the best player can forget what's happened... I like to make some sort of campaign log that is accessible to the players. Maybe a thread in your forum, or a sub-forum, or a shared Google Doc. You can keep it updated, or allow them to help in whatever capacity you're ok with, and you can always refer them back to it if they forget something campaign-related.]
3. Check how engaged in the recruitment process applicants are. I know it can be tough to gauge this, but it's helpful when you can. If an applicant's one and only post is their application, and they slide it in just before the deadline after recruitment has been going on for 2 weeks, it doesn't bode well for them checking in on your game. On the other hand, if they want to work with you to develop a character that really fits into your game, and there's a lot of back and forth between you, they're likely to stick around. Again, don't necessarily rule people out if they only post once or twice, especially if those posts are jam-packed with all of the other things you're keeping an eye out for (like following all the directions, making a good character, meeting the deadline, etc.).
4. Require a completed sheet, and check it. If you're running a game that requires character sheets (which is most games), this is important. It's not quite as important for games that don't have formal character sheets, but there's still probably something you need from them, and you should check it over. If they can't get around to making a sheet by the end of recruitment, they're not going to get around to much of anything else. Sometimes, they will submit an incomplete and/or incorrect sheet. It's important to check over the sheet and make sure they've got everything up to your standards. It's up to you how many T's need to be crossed and I's dotted, but make sure that they meet your requirements. Don't hold it against them for not following directions if you're not super-clear about what needs to be complete on their sheet, but you should expect the basics. I run D&D 5e games, so for me that means checking ability scores and mods, proficiency bonuses, items, attack and damage rolls, initiatives, character personality stuff, feats, spells, etc. (I also generally require at least an attempt at some sort of character biography, though I'm not strict about how detailed it has to be.) These things are virtually essential for a character to function properly, so it's important for the player to have them completed and correct. It's up to you if you're willing to work with players who are new and don't know, but I would encourage you to do so - everyone has to learn somehow, and people learn different ways. It's also up to your best judgment how much to dock an applicant (in terms of following directions) who takes a lot of back and forth to get everything complete and correct, but be patient and continue working with them until their sheet is done or recruitment is over. (This also helps you see how quickly they respond to your posts, giving you an idea of how often they'll post and building their engagement in the game).
5. Consider your applicants' experience. It's certainly ok to understand this to be their experience with RPGs or even your particular game system, but I'm referring here to their experience with PbP and the Tangled Web. The Recruiting Office Rules mention this, but I'm going to add to it. I typically try to get at least one player who's been around for a while to serve as a sort of anchor and unofficial helper at bringing newbies into the fold, and I also try to get at least one player who's relatively new so that they can get into a game. It's a toss-up for the rest of my players. You might try to keep it balanced with roughly 1 new(ish) to 1 veteran player, but it's really up to you. If the newbies drop out, you're still left with a few veteran players to continue on, and you can recruit a few fresh faces rather than having to end the game and/or start from scratch.
6. Keep an up-to-date list of completed applications in the first post of your recruitment thread. This is helpful for a number of reasons. The applicants can see if they're done, or if you need something else from them. Don't neglect to actually respond to their posts and provide information to them about what you need from them (after checking their character sheets, or for any other reason), but the list provides a constant and easy-to find reference for them. It also helps players who haven't applied yet to know if there's a glut of one type of character being submitted, in which case they might decide to submit a different type of character and increase their odds of getting selected.This helps you to balance the characters in your game, as I mention below. I typically include the applicant's character's race, class, and a link to their character sheet.
7. Look for the best fit in terms of player personality. Think about how they have communicated with you and with others. Were they helpful, sarcastic, to-the-point, or what? How did this make you feel about them? How did it seem to make the other applicants feel about them? Assume that they're going to act that way forever. Would having them in your game make it fun, or would it make it a drag and stress you out? You know what to do here.
8. Look for the best fit in terms of character personality. If you have an applicant who wants to play as a high elf paladin of Corellon with a special mission to exterminate all drow, and an applicant who wants to play as a drow, things are probably going to be difficult. Sometimes contrasts and conflicts create interesting, character-building moments. Sometimes they force players to compromise their vision for their character for the sake of the game, resulting in hurt feelings. Sometimes the player is unwilling to compromise their vision and force you as the DM to make it work or else break the game. Think about how significant these conflicts would likely be in your game, and, if you're really interested in both characters, be ready to either re-do some things or work with the players to slightly re-do their characters. Otherwise, only select one of the conflicting characters.
9. Look for the best fit in terms of character balance. Unless you have a special vision for a game of only one type of character (like all barbarians), your game will probably benefit from a well-rounded group of characters. It may not be possible to cover every base with the number of characters you're taking for a group (and maybe you shouldn't try to cover every base - let the characters figure out how to adapt to and account for their weaknesses), but try not to pick characters so that they have a lot of overlapping strengths and weaknesses. Often, applicants will notice a specific gap in character applications (if you're doing #6) and help you out in this regard.
10. Look for the best fit in terms of your game. Which characters spark your imagination? Which ones seem like they were born in your world and lived in it their whole lives? Which ones have a rich backstory that doesn't conflict with the core fundamentals of your game? These characters inspire you, which will help you make your game better, which will help keep your players around and engaged. Be open to work with players on their characters in this regard. Some will seek this sort of interaction (which scores them points for engaging in the recruitment, as mentioned in #3), but don't be afraid to bring it up to them even if they don't. See how they react to your ideas (and how quickly they respond). If they're open to them and seem excited about them, they're now more invested in your game. If they get upset about you suggesting changes to their character, they are inflexible and probably will derail your game to create the game/story they want for their character.
These ideas are not listed in order of importance, and it's your call which ones are more important to you and your game, but hopefully they give some insight that will help you select a good batch of players and have a fun, long-lasting game.