The APR on your credit card shouldn't matter a ton (of course you want a low one, but regardless), because you should never pay a cent of interest on it. You want to use the card and build some credit, but you don't want to make any purchase that you can't afford to pay in full at the end of the month. This will keep you from falling down the slope that Met described, while still building some credit, raising your limit, etc. Now, if you choose to use your credit card in this manner, which I highly recommend, the only thing you need to do is pick the one with the best points/rewards/miles/whatever because if you're using it this way, they're all essentially the same. You also want a card, as Pogo stated, with no annual fees.
When I started college I got a student Visa that had something like a $600 limit. Having used the card over the past 8 years as described above, I've never paid a penny of interest and now have something like a $4,000 limit. When I finished college I got a second card with airline mile rewards. I use both cards each month still, for almost everything, and just remain disciplined that I won't make a purchase that I can't pay in full at the end of the month. The result is an excellent credit score.