Earn more, burn less: Maximizing your frequent flier miles

The next time you make a withdrawal at the ATM, light a match and set your cash on fire. Does that sound like something you'd ever do? No? Well, if you book an airline ticket without considering the miles you'll earn for it, you may as well be throwing your money away.

Just by enrolling in your airline's frequent flier program, you'll be able to start accruing points toward free travel immediately. On a single trip, you can earn thousands of miles for the flight, plus bonuses for booking on the Web and checking in online or at an airport kiosk, and additional miles depending on the route you travel.

For example, US Airways just announced a minimum 7,500-mile bonus for winter flights to the U.K., even on their cheapest fares. Considering that you'll earn at least 5,000 miles for a round-trip to London, that bonus will get you more than halfway to a free ticket. And that's not even counting the additional bonus US Airways is offering in honor of its 20th anniversary (up to 20,000 bonus miles when you book multiple trips). If you're flying from the East Coast, fares to the U.K. start at about $300, including all taxes and fees. So it's practically worth taking the trip just for all the miles you'll earn.

On the other side of the coin, the fewer miles you can spend for an award ticket, the more you'll have left over for your next vacation. If you're planning a dream vacation to Mexico and don't already have a preferred airline, it may be helpful to know that an coach-class award ticket on United will cost 35,000 miles, while you can get the same reward for just 30,000 miles on American or Delta.

You can also save award miles by traveling during off-peak seasons. For example, US Airways will let you book a domestic award ticket for 20,000 miles, instead of the usual 25,000 miles, if you're flying between September 15 and February 28. And American offers off-peak awards to Mexico and the Caribbean starting at just 25,000 miles.

Sometimes airlines will run special promotions that let you book an award ticket for a reduced amount of miles. American and United, among others, are offering short-haul flights for just 15,000 miles this winter. And American publishes a quarterly list of destinations to which AAdvantage MasterCard holders can fly for at least 5,000 fewer miles than normal. For example, you can travel between January and March to Seattle or Vancouver for just 20,000 miles, Hawaii for 30,000 miles, or Lima, Peru for as little as 25,000 miles.

When the least expensive awards aren't available on the flight you prefer, most airlines will let you book a free ticket regardless, as long as you're willing to spend twice the amount of miles (for example, 50,000 for domestic travel). But it's rarely a good idea to use all those extra miles on a free trip. Because miles have a value of 1 to 2 cents each, you'll essentially be wasting a few hundred dollars in airline currency by booking that double-price ticket.

In a future article, I'll describe strategies for finding award tickets at the cheapest levels. Because while burning your miles is an excellent idea, there's no reason to let your frequent flier balance go up in smoke.

My next column will appear on December 14. In the meantime, I hope you'll take a few minutes to read any entries you've missed.