Make sure you get a card that doesn't charge monthly finance charges. I used to have one through anchor bank that charged me 20-30 bucks/month whether I payed it off in time or not. I was young, in college and just thought "oh cool, a credit card" and didn't think much else of it.
As I said in another thread, I now have a gas-based rewards credit card where if I pay it off in time not only do I incur no interest, I actually receive rewards back!