If you aren't paying off your balance in full then those fees will be earning interest against you too. (creditcardsmarts.org)
But, you can avoid paying any interest by paying off your balance in full each month and making all your payments on time. (credible.com)
The better tactic is to use your cards regularly for small, reasonable purchases and pay off the balance in full before the end of the billing cycle. (creditrepair.org)