Hmm, since I usually have problems finding people to debate with it helps to start one of you take the stance everyone else doesn't. It's just a way to test your own beliefs by attacking them yourself. Not as good as a really convinced opponent by a long shot - but almost as good. It's a basic tool in writing philosophy papers, as well. You always look for arguments against your position and then think about how to defeat those, and so on.
It's also how debate clubs work - you don't get to choose your stance, you're assigned.