It sounds like a no-brainer. You receive your credit card in the mail, along with a note that tells you, among other things, to sign the back of your credit card immediately. Lately, people have seriously questioned this course of action, pointing out that if your card is stolen, a thief then has a perfect copy of your signature to duplicate. Instead, say many, in the space for your signature on a credit card, you should write 'Ask for Photo I.D.'

It sounds like good advice. But what do the experts have to say? According to all three major credit card companies - Visa, Master Card and American Express, the answer is - sign your credit card immediately. In fact, all of them have rules that prohibit merchants from accepting credit cards that don't have a valid signature. Visa states that a merchant may not complete a transaction UNTIL the card is signed.

Bottom line on the question of whether to sign your credit card, then, is yes, you absolutely SHOULD sign your credit card as soon as you get it. But what about other security measures you can take to guard against credit card fraud? Here are five security tips to help you safeguard your credit card security:

1. Never give your credit card number to someone that calls you on the telephone. If the caller purports to be from a company that you do business with, or from the credit card company itself, tell them that you'll call them back at the number that YOU have for the company. That way you'll know that the person you're speaking with is legitimate. If they demur at all, hang up immediately and call your credit card company's fraud line with any details of the call.

2. Ditto for any email you receive asking you to 'verify' details for your credit card info by clicking on a link in the email to take you to a verification page. If it's a company with which you do business - PayPal for instance - open a new browser window and type in the URL to the legitimate site by hand.

3. Keep a separate low credit limit credit card for paying online - or use a credit card company that will provide one-time verification numbers. That way if your credit card security is compromised, you're losses are limited by the amount available on the card. Or - use a debit card that you keep just for online purchases the same way.

4. Reconcile your credit card bill every month just as you would your checking account. Go over the bill with your receipts, and report any charges for which you don't have a receipt or don't recognize.

5. If you have the option, register all your credit cards with a credit card registration service. In any case, write down all of your credit card numbers, expiration dates and contact telephone numbers for each card and keep it in a safe place. If your wallet and credit cards are ever stolen, you'll have a handy reference to make sure that you don't miss anyone when you're calling to report your credit cards stolen.