This report now available makes quite interesting reading.
The most common type of credit card fraud occurs is called *Card-not-present fraud* and makes up about 87.5% of all payment card frauds. Sometimes the card company will not reimburse you for this type of fraud, so it is worth being aware of the problem.
Here are two examples but there are many more.
1) Someone buys and then quotes a valid card detail either online, by telephone or mail order and then later the owner of the card, calls and says "Hey what is this about?" I would suggest that if you take over the phone credit card details, you do so only with customers you have dealt with before,
2) I have heard of a merchant that got burnt when a person used a card in the shop that for some reason did not when he did a swipe work. The merchant then manually entered in the card details. Only later did the merchant discover that the card was counterfeit. In this case, I would suggest that you have a policy in the shop that if a card does not work, ask the customer for a different payment method or card but do not enter the card number manually.