The Federal Reserve decided to cut interest rates by at least 75 basis points. What do you need to do about it? Keep making payments on time and chip away at existing balances.

"Those consumers whose interest rates are tied to the prime rate as an adjustable index, and who are not subject to a minimum APR (or "floor") that may limit APR decreases at this time, would see their card interest rates drop the next time their pricing agreement calls for an APR review and adjustment," Ezra Becker, principal consultant at TransUnion's Financial Services Group, wrote in an e-mail.

Those lucky enough to get a rate decrease should see it take effect within three billing cycles. They shouldn't break out the firecrackers, though.

"If you get the cut, great. But never assume that that cut's going to be permanently reflected on your account," says Curtis Arnold, founder of CardRatings.com and author of "How You Can Profit from Credit Cards."

If your credit risk changes, your rate could head north or your limit could get whacked at the knees. In fact, as many as 60 percent of U.S. banks said they had reduced the credit limits on the accounts of subprime cardholders, according to the latest senior loan officer survey.

Keep your credit score as high as possible so as not to receive any adverse actions. Pay your bills on time and reduce balances as much as possible. Reach out to your lender if you're having trouble making the minimum payments. Many banks have in-house workout programs that can lower the interest rate or waive fees for a short period of time.