I wish I'd known to:
1) Outline early,
2) Get a hornbook for each class,
3) Read "Getting to Maybe" before school starts,
4) Recognize the fact that we're all going to die. One shouldn't rationalize that fact by never studying, but come on - overall, do you really think you're going to be a better/more likeable/more fun/more well-rounded person by studying in the library 18 hours a day? It's important to take advantage of this opportunity to learn, but equally important to enjoy one's youth.