to build credit go ahead and apply for a new credit card, not a prepaid. Make sure to stay below 50% of the card limit. I have a card w/ a $500 limit just for building credit and I have had that since I was 18. Also, go out and buy something like a living room set, a diamond ring for your girls, or something equal to that (a newly used car perhalps) and put it on store credit. Even if you have the money up front it will help to build the credit. Or, with no other options, if your parents are paying for a car have them put your name on the lease/bill.

G/L building credit, it can be your biggest help or your biggest downfall.