- Casual. May hit a raid-type target if enough people are on.
- Mature. This really doesn't mean age.
- Enough members on the roster so that guild groups can be had. (I'm willing to help a guild grow, assuming the other criteria are met.)
- Friendly and social. Willing to help others, guilded and not.
- Members are smart enough to have windows and/or filters set to not miss /g, /gu, or important combat messages, or to know how to ask for help.
- Has a No Asshole policy.
- Balls enough to warn/kick immature/asshole behavior.
The last two are important to me. When I'm tagged, and someone carrying the same tag is a jackass, I feel responsible.
I had elaborated on these points and had given more background about me, but it seemed better to distill it all down into bullets.