NEW YORK (MONEY Magazine) - These days, 60 percent of American households have cell phones, and they spend an average of $53 a month to use them.

Turns out, that sum may be considerably more than necessary. According to J.D. Power & Associates, only 72 percent of anytime minutes and 51 percent of night and weekend minutes get used each month -- an average of 61 percent of total minutes.

In other words, customers pay for nearly twice as many minutes as they use.

Scaling back on the minutes you buy is not necessarily the answer. As Roger Entner, wireless analyst with the Yankee Group, points out, "If you go 10 percent over the minutes you're contracted for, suddenly you double your bill."

So how do you navigate this high-wireless act?

Compare how many anytime minutes you've bought during the past six months with the number you've actually used. (Those "free" nights and weekends are a nice sales tactic, but most of us don't make the majority of our calls then.)

If your number is consistent from month to month, go for the plan that comes closest to your needs -- but don't lowball. If your usage is somewhat variable, Cingular's rollover option lets you "play a little closer to the edge," Entner says.

And if the number is very inconsistent, Sprint's new Fair and Flexible plan allows you to use varying numbers of minutes from month to month; the more you talk, the cheaper the rate.

Next, advises Allan Keiter, founder of Myrateplan.com (my favorite Web site for side-by-side comparisons of phone plans), see if you typically use your phone for 30 minutes or more a month outside your local calling area. If not, you don't need a national plan.

"People still confuse making long-distance calls from their home area with roaming," Keiter says.

The new in-network plans that many major carriers have recently rolled out sound terrific. But if you go for one because you spend a majority of your minutes on the phone with your spouse, be sure you're talking wireless to wireless most of the time.

And if you're banking on the fact that free nights and weekends will allow you to stop using your landline at night, make sure that you actually do so. (Set up a charger near your landline, and put your cell phone there every evening to remind yourself to use it.)

You can and should shop around for data services -- text messaging, surfing the Web and so on -- as intensely as you shop for minutes, says Myrateplan's Keiter.

Rates are all over the map. With Sprint, for example, you'll pay $5 for 100 messages, or 5¢ apiece. At Nextel, that same $5 buys 300 messages, less than 2¢ each.

A prepaid plan includes taxes, fees, surcharges and overages as well as minutes. That's a clear advantage if you need to know how much your monthly bill will be.

Yes, the minutes look more expensive -- an average of 24¢ vs. 16¢ on a pay-as-you-go plan, according to TRAC, the Telecommunications Research and Action Center in Washington, D.C.

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A better comparison: Look again at six months' worth of your bills. Divide the bottom-line number on each bill by the number of minutes you used, and see how the average result stacks up against the per-minute cost of the prepaid plan you're considering.

Finally, if you suspect you're overbuying, ask your carrier for a plan that better suits your needs. Most providers would rather accommodate you, says J.D. Power wireless analyst Kirk Parsons, than lose you to a rival.

Editor-at-large Jean Chatzky appears regularly on NBC's Today. Contact her by e-mail at moneytalk@moneymail.com.