Lifehack.org has a list that I keep re-reading. I think I agree with most of these. It’s called 34 tips for your younger self, but I think a lot of still applies to your current self:

2. Follow your passion, even if it does not pay very well. If you are good at what you do and love your career choice – the money will eventually follow.

3. Now is the time to establish good habits for life in every area; they might take a lot of hard work to form, but it’s worth the effort and missed television.

4. Listen more, listen better, pay attention and remember! Many people have been there and done that and can save you some headaches—but only if you listen.

5. There are some narcissistic whackjobs and bitter people in the world who will make your life a misery and who are so firmly embedded in their own version of reality that they’ll never change. Should you have the misfortune to encounter such a person, in whatever capacity, don’t hang around any longer than you absolutely need to.

update: added the URL up there…