I graduated college 5 years ago and wish I'd known this earlier: the specific knowledge you learn matters less than learning HOW to learn. Develop good study habits and critical thinking skills and you can adapt to any subject or career.

Don't pull all-nighters. The research is clear that sleep is when your brain actually consolidates what you learned. Studying until 3am and then taking a test exhausted is worse than studying less and sleeping. Trust me, I learned this the hard way.

Strunk and White's 'The Elements of Style' is a tiny book that will make you a better writer almost overnight. Every student should own a copy. It's cheap, it's short, and the advice in it never goes out of date.

Flashcards still work. Old-fashioned index cards. Make them yourself — the act of writing the card is half the learning. Quiz yourself, shuffle them, put the hard ones in a separate pile. Low-tech but it gets results.