I used to dread having to form groups where you have to pick your own, but I think I've been in so many groups now that it doesn't bother me to just ask around and see who wants me in their group. Actually, this semester for the most part people were approaching me, which made it easy. I've found that it's not really that big of a deal, and even if you don't know everybody that well or are even friends with anybody, people are generally friendly and most likely will not turn you down flat, or will be polite about it- like just saying that they already have enough group members. But even apart from class projects, I always feel like everyone around me has formed their own "cliques" that I'm somehow always excluded from or have no idea how to break into. But for class stuff, I just suck it up and ask around until someone will work with me. It doesn't usually take that long before someone says yes, and I know I always feel very relieved once I have a group to work with.