If you're going to carry a balance on a new credit card, look for a low interest rate.

For many people, credit card annual percentage rates, or APRs, are averaging between 13 percent to 15 percent, says John Ulzheimer, president of consumer education for SmartCredit.com. "But some issuers are going as deep as 7.9 percent on their rates."

You can also use zero percent introductory rates to your advantage.

Thanks to the Credit Card Accountability, Responsibility and Disclosure Act of 2009, or CARD Act, introductory rates have to stay in place at least six months, as long as you pay on time. So you have that period to put your entire payment toward your balance, he says.

If you're taking advantage of a balance-transfer offer, make sure you understand how the transfer affects your credit score.

Pro tip: Don't close the old account after you transfer that balance, says Ulzheimer.

While your credit score could take a small hit when the new credit card issuer checks it, having additional credit at your disposal could actually improve your score over time.

Remember not to start running another balance on the old card. Use it just enough -- once every few months for something small, and pay it off in full -- to keep it active.