I've never been to one, either, and have similar questions. Looks like there's nothing to fear. As far as things in common, you might really be surprised. Everyone has a family of origin; ask about theirs. Everyone has/had/wants
a job. Ask what theirs is/what they'd do if not doing their current job. Everyone has people important in their lives, favorite places they've been. And everyone likes to feel heard. So if you go with the thought to make someone feel heard by listening, you will make a friend by being one.