Credit scores are worth checking to get a sense of your credit risk. Most lenders use FICO scores, which you can buy at myFICO.com. Each credit bureau also sells a credit score, which you can add to the purchase of your credit report for a few dollars.

10. Monitor transactions
To protect yourself against wrongful charges and credit card fraud, reconcile receipts with your statement, and dispute errors with the issuer. Doing this allows consumers to withhold payment on the disputed amount. "Consumers need to know they can't withhold payment on the entire bill," warns Bockstein, because they'll get slapped with a late fee and a higher interest rate.

Don't assume you can't be a credit card fraud victim if you still possess the card. Fraudsters can use skimming devices to steal information from the magnetic strip on your card and create a counterfeit copy. Report suspicious transactions to your issuer, and you are only liable for $50 in fraudulent charges.

11. Call for a lower rate
Call customer service once in a while and ask for a lower rate. Mention offers for lower-rate credit cards and the issuer may accommodate your request.

"If you've had a late payment or gone over your credit limit, wait at least six months before asking for a lower rate," suggests Kristine McKinley, a Certified Financial Planner and CPA at Beacon Financial Advisors, based in Lee's Summit, Mo.

12. Know when to switch cards
If you dutifully follow these tips and your issuer still jacks up your rate or reduces your credit line -- and doesn't negotiate when you call -- it may be time for a new card.

"Move your business elsewhere if you've done nothing wrong and they start changing the rules on you," says Ewing of Bills.com.

When paying off the balance isn't an option, consider a balance transfer. The story, "5 balance transfer trip-ups," explains how to avoid expensive mistakes when moving your balance to a new card.