If you had to do it all over again, would you do anything different when you first started gaming?
When I was young I actually did not game that much. I felt that I had to have a complete mastery of the rules before I started playing. This was especially tricky when I started to buy GURPS books. I didn't realize that most people did not know every rule of D&D, and that half of the fun was making stuff up on the fly to cover crazy situations that the players and DM came up with.
If I could do it over again I would spend less time trying to memorize rules, because I think that it is impossible to remember all of the rules for D&D. I would play more, and make up house rules as I go. This is my philosophy now when it comes to gaming. Play first, rules second.