After straightening up her personal finances and routinely paying off her credit-card balances in full and on time each month, a Maryland occupational therapist says she realized she's no longer the customer credit-card companies desire.

Her question: "Are there credit-card companies that might offer me rewards or appreciate me?"

In other words: What creditor wouldn't prefer a consumer who builds colossal debts, then takes forever to pay them off while paying out high interest charges? That's how the credit-card industry makes 75 percent of its revenues.

Some credit-card companies even punish conscientious bill payers -- fining them for good behavior or reducing their grace periods to make on-time payment trickier.

"Credit-card issuers consider cardholders who pay off each month deadbeats," says Robert McKinley, chief executive officer of CardWeb.com, a Frederick-based Internet service that tracks credit-card industry news and helps consumers select the best cards.

Still, 40 percent of cardholders avoid interest charges by paying their bills in full each month, according to CardWeb.com.

Gerri Detweiler, author of "The Ultimate Credit Handbook" (the third edition ships this month), says there have never been more reasons for consumers to pay off balances on time.

Card issuers "are penalizing consumers who are even an hour late with their bills," she says. "Most have high late fees -- as high as $39 -- and many raise your interest rate if you are late with a payment."

Some issuers even raise interest rates when customers make a late payment on other bills and it registers on their credit reports, Detweiler says. "An example: AT&T Universal Card promo offering 0 percent interest until May 2004 -- but if you are late on their card or any other card, the rate goes to 19.95 percent plus prime!"

Consumers in search of the right credit card face a dizzying array of interest rates, annual fees, promotional incentives and penalties, not to mention the fine print. The key, say credit experts, is to know how you're going to use the card.

"If you think you may want to carry a balance, then look for the lowest rate," says Detweiler, whose Web site (www.ultimatecredit.com) helps consumers with credit questions. "If you pay in full, then go for cards with free rewards or rebates."

But that means weighing the rewards against the annual fee. "Cards that offer frequent-flier miles, for example, usually charge higher annual fees -- perhaps $50 or more," she says, recommending that consumers calculate monetary value of frequent-flier rewards at two cents per mile.

The best credit cards for convenience users? McKinley recommends Diners Club, American Express and Discover. "Diners offers the ability to accumulate rewards on all purchases with the option to transfer the points to many airlines, hotel programs, etc. It offers the most flexibility with reward redemptions," he says. "AmEx also offers a variety of rewards. Both cards carry annual fees, but this can be offset by a high charge volume.

"Discover offers cash back based on purchases, and there are several good deals among VISA and MasterCards, such as the GM MasterCard, which offers a rebate toward a GM purchase," he says.

Got a consumer complaint? Question? E-mail details to oldenburgd@washpost.com or write Don Oldenburg, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071.