From what you've said, I see no reason why you can't become a good modder. I certainly don't consider myself to be a good one--I just tweak things and sometimes I get lucky. Racerboy gave you some great material to read through and Ducimus gave you Excellent advice. Most of all, remember that...
...There's always room for another good modder
!
Wishing you success and--most of all--Enjoyment with your goals!!!
Peto