Check your statement each month to be sure you are still at the interest rate you signed up for

From: simplejoe.com

Don’t apply for a card unless or until they tell you what your actual rate will be. This is hard because most of them are not set up to tell you. Generally you will need to know your credit card processing scores and have a copy of your credit report handy. Even then you are unlikely to find someone through their telephone maze that will or can actually answer your question. Try to find a card that gives you a confirmed rate before you apply. A reliable company will first request a copy of your credit report from one of the credit bureaus before quoting you a rate. Often smaller banks and companies offer better deals and are not as strict or hard to deal with. Check with your local banks also. At least with a locally issued credit card "you know where they live".If your rate has been increased, look for a late payment fee, or some other reason for the increase. Call the company and ask them why they increased your rate.