Q. What should I consider when weighing a card with mileage points or other incentives against another card?

A. People love the thought of racking up points, but the points are worthless if you don’t use them. Before signing up for a rewards card, check the limits of the program. Some restrict the stores where you can shop and receive points; others cap the number of points you can accumulate. Look at the interest rate, too, since rewards cards often carry higher rates and, occasionally, fees.

Your best bet is to keep a rewards card for smaller, everyday purchases that you’ll pay off in full each month and a low-interest card in case you need to carry a balance.

Q. Is it better to keep a big balance on one card or spread the balances over several cards?

A. You’re usually better off keeping smaller balances on a few cards “If you have just one card and it’s almost maxed out, that suggests (to your bank and other potential lenders) that you’re having trouble getting credit,” says Robert D. Manning, Ph.D., director of the Center for Consumer Financial Services, at the Rochester Institute of Technology, in New York.

The exception? If one card has a particularly low interest rate, you might want to switch all your balances to that one to save money.