Two Rules (and a secret third rule)

I basically have two rules when it comes to deciding who gets to play at my table:

1. You have to want to be there. If you'd rather be away doing something else, please go and do that thing. If you're only here because your boyfriend/girlfriend/parent/other dragged you along, please be elsewhere (and for that other person: please go and work on your relationship elsewhere!). But in terms of race, sex, sexuality, religion, or any other category... I don't care.
2. By your actions, both in-character and out-of-character, you need to make the game more enjoyable for all present, not less so. It's fine for your character to be a jerk, as long as they're an entertaining jerk. And intra-party conflict is likewise fine, as long as it's all in good fun. But as soon as it stops being fun, I expect it to stop.

And the secret third rule:

If you're not going to make it, you must let people know. You don't need to say why, but you do need to say. Pretty much the only exception to this is if someone ended up in the hospital - otherwise, we live in a world of ubiquitous communications, so I expect you to use them.