I belong to two writers' groups, each loosely connected to the other. There are certain things I like about each group and certain things I don't like. With that in mind, here are my own "writers' groups dos and don'ts."
DO find a group you mesh with personally and aspirationally. Sure, there will be some in the group you don't mesh with, but on the whole you want to work with people you get along with and who have similar goals. Our group might have its moments, but any dispute or ill-feelings is quickly rectified. We also share the goal of being published and those of us already published yearn for more.
DO attend on a trial basis and DO check out more than one group. When my son joined Boy Scouts we just automatically went to the troop attached to the pack. Big mistake. We should have shopped around.
DON'T join a group steeped in formality. When I joined my current group (a small group of about 6 writers, which I think is ideal) it was just coming out of the throws of uber-formality. It had a registered name, officers, and a budget. What happened? Power struggles and ill feelings. Unless you have a super-large group this type of formality isn't really necessary as certain individuals will step into informal leadership roles. In my group, I'm usually the one to send out the "who is going to be there this week" email.
DO be open to feedback - that's why you're there. If you are there to reap praise on your work, have your mom read your stuff. But if you want serious feedback on how to become a writer, be open to suggestions. You don't know everything.
At the same time, DO be respectful with your own feedback. Early on, a member of my group (who is no longer with the group) told me she'd chuck my writing in the trash. Ouch. Instead of making a blanket statement like that, offer suggestions for improvement. It's a give-and-take. You offer some suggestions, you take some.
DON'T argue your point unless you are explain your reasons for a particular passage or wording and are ready to receive feedback on its effectiveness. "That's just the way I want it to read" is not a good defense. Just take the feedback and if you don't want to make the change, don't. However, there have been times when someone has asked my inclusion of specific information at which point I offer my reasons, such as trying to set up a future plot point, or giving insight into the character's personality.
DO remember that you are there to learn and become a better writer, but ultimately it's your own work. At first, I wanted to incorporate all of the suggestions made, but many of them were contradictory and sometimes I'd lose my own "voice." That's not good. It takes time to find the right balance but I am the first to say that I'm a much better writer now than I was three years ago when I first joined the group and anything I write that gets published is as much a credit to them as it is to me.
What about you? Do you have anything you'd like to add to the list?