If you owe $200 on one credit card and $1500 on another credit card, pay the smaller debt first. When you get rid of one credit card debt, you will have a taste of success at paying off your debt.
If there is a card that has an outstanding balance that has not reached the due date, pay down the debt for this card first, if possible. Because the due date is not reached yet, there is no interest rate applied on the amount, paying it soon means no extra payments.
If you owe credit card debt to several companies, find out which one is charging the highest interest rate. Payout the debt on the credit card that is charging higher interest because if you left the debt unpaid for longer, it may compound high interest over time. This why the sooner you pay off the debt, the better.
This method is known as the balance transfer method. If you own a high-interest rate credit card that requires huge interest payments from you in each period, transfer the outstanding balance to a low-interest credit card account if your lender allows it. You will have to pay less debt if paying down your debt is going to take some time.