I'd say I would go into the past and warn myself about everything that would happen to me (lol I know, seeing yourself, whole world implodes what the hell ever) That way, I'd be much better off now, as I could avoid the women that suck, and talk to the women that are good, and actually ask out the chicks that had crushes on me that I never knew about until way too late.
Also, the fourth chance with the right girl where everything would have gone right would be the first chance and I wouldn't mess things up. Perfect.
Oh yeah and make a lot of money, develop something, kill something, have sex with Tauntaun, whatever generic EB answer.