@Pyrephox very much agree with setting boundaries in particular. I have seen it (rarely) done well, and it was amazing the difference it made in the behavior of /everyone/ on the game and how they treated each other--even if they'd played together for years on other games. And how quickly things really devolved into the usual when boundaries started to slip as far as their reinforcement.
It's very hard and taxing work though, especially over the long haul. People often mistake being a hardass for being good at boundary enforcement. ("I'll kick people who do that off my game if they show signs of tantruming/being weird or mean on channel!" while they ignore the people they know or excuse them having a "Bad day" on a consistent basis.) Holding respectful boundaries in any org, online or otherwise is a lot more work than a lot of people give credit for!