Honestly, I barely scratched the surface. There are countless firsthand accounts of him doing things that should not have worked. Aside from all of that, he mastered the art of the Fighting Retreat, wherein he kept the Continental Army relatively intact, falling back in good order, and fighting every step of the way. He "lost" pretty much every pitched battle, in that he gave up ground, but successfully attritted (which is a word, Google; update your dictionary) the British over the course of several years.
Also, Jim's right about Valley Forge; it was arguably the most pivotal moment in the American Revolution. Not just because morale was low and the Continental Army was almost out of supplies, but because it gave the troops time to actually learn how to fight. Baron von Steuben (a Prussian Baron who had a score to settle with Britain after the Great War for Empire) took the opportunity to drill the Continentals, teaching them basic firing discipline. He used a very simple method; drill and instruct 120 soldiers, who then went and instructed the rest of the army.
He's one of the unsung heroes of the American Revolution, someone whose name everyone should know, but I don't think I've ever met someone who did except for my dad and my old professors. Anyway, when the Continental Army left Valley Forge, they were far more effective than they ever were before.
Final fun fact: Von Steuben Day is actually a holiday in the US. It's September 16th this year. Fire some muskets to honor his memory!