You're young, you have a full-time job, but you presumably don't have a very long credit history (unless you've been working and paying a lot of bills since you were, say, 13). Unless you've had a car repossessed or a cell phone account sent to a debt collector, your credit is probably in pretty good shape although it would be considered "thin" because you're just starting out.

Since you want to build credit, I'd recommend you choose a card that encourages you to pay off the balance each month. A history of on-time payments and low credit usage are great for your credit score. If you're as well-disciplined as you seem, you would probably do well with a rewards card. Rewards are a great way to put some cash back in your pocket for the things you spend money on anyway.

That's the key right there--money you would have spent anyway. Don't be swayed into buying more than you can afford just so you can get more points. And be sure to pay off the balance each month, or the interest charges will quickly wipe out any rewards you earn.

Whatever card you get, please don't carry revolving debt, but if you do, make sure you can easily pay it off in two or three months, tops, and don't keep spending with the card while you're paying off that revolving debt. I wish someone had drilled that message in my head when I was 22.