1) Play well with others. He's collaborated with Cee-Lo Green for Gnarls Barkley, MF Doom on two albums, David Lynch and Sparklehorse on Dark Night of the Soul, and now with James Mercer of the Shins. He's produced an album for the Rapture, the Gorillaz, and Beck. He's worked with so many cool people and it always turns out awesome. I'll bet there are kindergarten teachers all over the world thinking to themselves "why can't these kids be more like Danger Mouse?"
2) Share things. Okay, so he ignored the "don't take things that aren't yours" rule for the Grey Album. But to be fair, Jay Z is a very tough guy to get a hold of, and I'm sure that if they were classmates he'd be like "sure Danger Mouse, you can borrow my beats for a while, let me get them for you from my cubbie."
3) Always clean up after yourself. He probably does; beards take maintenance.