In order to avoid credit card skimming the number one practice that you should adopt is to never let your credit card or debit card out of your site. Credit card skimming incidents can be difficult to spot in the time that you actually notice fraudulent transactions on your credit card bill. For this reason it is important to monitor your checking and credit accounts on a regular basis and report any an authorized transaction suspicious activity.
Be especially careful in places where your credit card is going to be out of your sight even for a short period of time such as gas stations, restaurants, bars etc. These are the places where credit card skimming happens the most because the consumer feels secure in putting his credit card in the hands of another person and letting it out of his sight, even if for a short while.
Be careful at ATM machines. Sometimes thieves put a camera near the keypad of the ATM machine in order to record the pin number. They may also put a false keypad on top of the ATM machine keypad in order to record your keystrokes. Check if there is a strange looking device attached on the side or under the ATM machine close to the slot where you swipe your ATM card. If the keypad of the ATM fee is particularly hard to press walk away and use another ATM machine.
You can also do a search on a search engine and get familiar with how credit card skimming machine is like. They can be pretty small and unobtrusive but knowing what one looks like may help you spot one.
There are also scams running where someone promises to clean your credit card by cleaning up the magnetic strip behind the credit card. What they do is swipe your credit card through a skimmer and steel information on your credit card.