Don't let anyone swipe your card twice without giving you a 'transaction cancelled' receipt for the first swipe - card 'skimming' is growing where fraudsters swipe cards through a second machine to record details.
Be on your guard when withdrawing money from ATMs - if anything seems out of place with the machine or people around you, don't transact. Check particularly for small skimming devices placed over the card slot.
Hang onto ATM receipts as proof of your transactions.
When buying over the Internet, deal only with reputable online merchants whose sites offer full security. Check for the padlock symbol at the bottom of your web browser.
A good point to always look out for is when you are in a restaurant don't let the waiter take your credit card away always make sure you are present when your card is swiped. Friends of mine let the waiter take there card and unbeknown to them the card had been put through another swip machine that took all the details of their account.
