As leader of several somewhat successful* projects, the only advice I can really offer is to just be friends with the people you're working with. It makes it feel less like a "business" where you're a boss and more like a group of friends that all listen to each other. Me and the SST team all screw around on IRC all the time and make weird chanserv scripts, talk about poop, send each other 4chan links, etc. I'd say about 4% of our group discussion is actually about modding. That's not to say that we're not productive, although I suppose that's actually true of us. We're all lazy kids.
Anyways, all I'm saying is that it's easier and less stressful to work on a project with people who are friends first, modders second.
*(as in playable and generally well-recieved)