Newsweek has 10 tips for avoiding credit card pitfalls:

•Be aware that the card issuer has a great deal of leeway. They reserve the right to change the terms of your card, including the APR (annual percentage rate), at any time, for any reason--with as little as 15 days notice. So check your monthly statement carefully.

More inside.

•There is no limit on the fee a credit-card company can charge a cardholder for being even an hour late with a payment. That's due to a 1996 U.S. Supreme Court decision (Smiley v. Citibank) that lifted the existing restrictions on late penalty fees. Today, $30 is the most common late fee, according to the Consumer Credit Counseling Service. Ten years ago, that number was $13.

•There is no federal limit on the interest rate a credit-card company can charge. Take a look at your credit-card statement. Most likely, the return address is located in a states where state governments have weak "usury laws."

Plastic Predicament [Newsweek]