her are a couple I've heard:
Roy M. Cohn: Go after a man's weakness and never, ever, threaten unless you are going to follow through, becuase if you don't, the next time you wont be taken seriously.
Stephen Ambrose: The past is a source of knowledge, and the future is a source of hope. Love of the past implies faith in the future
Yogi Berra: You can observe a lot by just watching
Then a very common one: Ignorance is bliss, my friend.

Then I was reading Exile's Honor by Mercedes Lackey (awsome autor IMO) and I read this: "Expertise can get you to good, but practice gets you to master" or something very close to that
I htink i'll post more later but I'll have to upturn my room to find the paper with quotes on it....