If I had it to do over again, say from 19. I would have put off college for a few years and joined some organization like the peace corp and traveled a little more. Or perhaps college first and then peace corp.
I did learn about LD whan I was 20, but didn't do anything with it for 10 years. What a waste!
I am just now in the last 5 years or so beginning to study meditation and altered states of conciousness.

I would have spent more time with my younger sister. She died this year at only 39.

One thing I wouldn't change though, I have a great family. My oldest is 15

---EDIT---
Been thinking about it, college first, then peace corps. I finished my first degree when I was 19. I went back and started working on my next when I was 30. It was a lot easier the first time!