Always, always, always make at LEAST the minimum payment on your card. (And remember that a 1,000 percent interest rate doesn’t even matter if you pay off your balance in full each month!)

Pay early. The fine print on your contract very likely requires payment not at midnight the day of your deadline, but by 10 a.m. Also, if you have a spotless record of on-time payments, your issuer is much more likely to waive a late-payment penalty should a problem occur.

Appeal any contested charges promptly and in writing. “You have only 60 days to assert an error,” says Jeanne Hogarth, manager of consumer education and research for the Federal Reserve Board, which oversees credit cards issued by state member banks.

Read the fine print on your credit card contract. And if you don’t understand it, recruit someone who does to explain it.

If you have a problem with charges that seem unfair and can’t make any headway with the issuer, go upstairs! At least five different federal regulators charter credit cards, but some cards (such as store-issued cards) aren’t under much regulatory oversight at all.

To discover which agency oversees your particular credit card, call the Federal Reserve Board at 202-452-3693 and follow the voice prompts, or search the name of your card’s issuer at fiec.gov/nic.

If you have a store card, contact your state’s office of consumer protection, your state attorney general and the Federal Trade Commission (ftc.gov). The FTC does not investigate individual complaints, but it does funnel the information about deceptive or illegal practices on to other law-enforcement agencies and sometimes takes action on behalf of groups of disgruntled consumers.