I used my dads old Remington 1100 when I learned to shoot trap. Was pretty good with it too.
In my opinion, I would actually start out on sporting clays.
If you can shoot sporting, you can pretty much shoot anything. If thats not your deal...try skeet.
I started on skeet, then sporting clays, now here at college Im competent in Trap, Doubles Trap, Skeet, International Skeet, and Sporting Clays
amen sporting clays is the most demanding the targets are never the same