Periodically check your cards to make sure they have not been lost or stolen.
Some thieves take only one card to make the loss less noticeable.
Review your monthly statements and call the credit card company if there are charges you did not incur. Don't loan your card to others, even family members. If you do not receive a new card when your card expires, call the credit card company. Don't put your payment and bill in your mailbox. Drop it in an approved mail box.