I believe the single most important thing I've learned from playing competitive online games is how to manage the morale of a group. When you have 30-minute experiments, mostly self-contained, it's amazing how easy it is to see how one denigrating comment can ruin a whole match because it ruins the teams cohesion and teamwork. A few well-placed bits of praise, a little humility, and a little leadership will trump raw skill most of the time.

It's a lesson I'm glad I've learned, and now I can use online games as a way to practice.