I usually just step in, introduce myself, and ask questions until I find something to talk about. THough of course, it depends on what the community is centered around.
Thoughts:
Hmmm. What's this place like? Do I want to be a part of this? Is this going to meet my needs?
And after learning more about the community
Are these flaws in the community ones I can deal with? Am I okay with being associated with this group?