I don't know that I'd do anything differently.
Even the girl who obviously liked me, who kept hanging around me, trying to start conversation, who even one day walked up to me and laid her head on my shoulder. Even when I froze up and couldn't move, and then started to squirm away and push her aside because I couldn't handle physical contact. Even when we never spoke again after that day. Even that, I wouldn't go back and change.
If I did somehow go back, it would've played out exactly the same way. You can't regret that which was inevitable and unavoidable.
I've been around a fair bit, and I'm starting to get past the point where I should've married by now. Most of my peers are getting started on the whole parenting business -- I've yet to go on my first date.
Actually, I take that back -- I would change something. I'd go back and make myself realize sooner that I'm simply not made for romance. Would've saved myself a lot of mental anguish in my teen years and early twenties.