You can avoid being charged interest by your credit card company by paying your balance in full each and every month.  Interest is assessed on your balance after it has been outstanding for one or more billing cycles.  If you are only paying the minimum payment on you accounts then the interest you are being charged will become compounded and it will take you a very long time to pay off your credit card debt.

The only other obvious way to avoid being charged interest is to apply for a card with a zero percent interest rate.  Most cards only offer zero percent APRs for a limited period of time.  Make sure that when the zero percent APR offer ends, you have paid off your balance in full – otherwise you will be assessed interest.