It can be hard. These devices that thieves attach to the card slot in order to capture account information from your card's magnetic strip have become more sophisticated. One tipoff: Most ATMs have a flashing light at the card slot. If the light is obscured, that's a sign of tampering. Other giveaways: a card slot that is not securely attached or has a different color than the rest of the ATM. Use ATMs in bank lobbies and other places with 24-hour video surveillance. And always cover the keypad as you enter your PIN, because a thief's spy camera may be watching.

You may also like: What's the best way to fight identity theft? >>

Sid Kirchheimer writes about health and consumer issues. Have a question for Sid Kirchheimer about a new product, a new kind of bank account? Check out the Ask Sid archive. If you don’t find your answer there, send a query.