I think it is a good idea to get a credit card and pay it off every month in full. This will build up your credit and will be good for you in many ways.

Just an example. I'm a college Junior and I've had a credit card for about a year now that gets paid off in full every month. Just last week I created my first cell phone contract in my own name. I didn't have to leave a deposit because my credit was good. However, a friend of mine, who has never had a credit card and I guess has no credit, had to leave a 500 dollar deposit to be held by ATT for a year.