Reducing credit card interest rate

Do a Google/Yahoo search for "Defalte Your Rate" and you should find a report that explains the basics of negotiating with credit card issuers for a lower apr. There are a few factors (like your payment history, age of the account, etc) that come into play, but the key is to have a competitor's balance transfer offer to "wave in their face" (nicely, though) to motivate them. This does not always work, but it sometimes does. One method is to turn the tables around and ask the credit card company rep "OK, you're charging me XX% APR and I have this balance transfer offer for a much lower APR and this would save me a lot of money. What would you do if you were me?"

That being said, your APR is not calculated as part of your credit score.