Did you know that you can call up your credit card company and ask to have your interest rate reduced? While they don’t say yes every time, they may suggest what you need to do in order for them to reduce the interest rate in the future.
This will usually involve paying more than just what the minimum monthly payment is – and doing that a few months in a row. I did that when I carried a large balance on a credit card during university – they dropped the interest rate 2%.