Since you never know for sure whether or not there's a skimmer device on credit card readers you use, any swipe potentially puts you at risk of identity theft. The best you can do is to avoid explicitly dangerous situations.
Savings.com suggest the following advice to keep your credit card info out of the hands of identity thieves:
* Look out for the abnormal. If you're at a familiar place and the card reader on the counter behaves differently in any way, cancel the transaction and ask the clerk to swipe it with the reader behind the counter.
* Be suspicious of self-checkout lanes. Since these machines aren't as closely monitored by workers, there's a better chance a thief has manipulated it. Your odds of exposure are still minimal, but those looking to be extra careful should consider shying away from self-checkout lanes.
* Select the "credit" rather than "debit" option. If you're going to be defrauded, it's better that the thief charge the money to you rather than take it directly out of your account. Credit transactions usually give you more leeway to fix fraudulent transactions.
Also, don't forget to stay on top of your charges online to make sure nothing fishy sneaks past you.