Wendy Perrin speaks with the pros to bring you strategies that will turn your frequent-flier miles into free flights every time

Do you have enough frequent-flier miles for the free tickets you dream of, yet are never able to cash them in for the flights and cabin class you want? You might be in need of a mileage makeover. Mileage programs have been changing lately, and the rules of the game have changed with them. With Continental joining the Star Alliance and British Airways joining the American Express Membership Rewards program, for instance, some people now have many more flights and routes to choose from, while others have far fewer options. At the same time, airlines are increasingly selling coach award seats for a combination of miles and cash, as well as letting you use miles to upgrade to business class from the cheapest coach tickets. And they're issuing new credit cards that enable you to buy your way into—or most of the way into—elite frequent-flier status, which means that big spenders are now competing with frequent fliers for free seats.

Which is why, if you're not able to redeem your miles or points for the flights you want, it could be that either you're in the wrong program or you're not employing the new tools and strategies you need in this changing landscape. Here's a step-by-step plan for using your miles to fly where you want, when you want, and in the best seat possible:

1. Make sure you're in the mileage program that best suits your award goals.

"Ask yourself what the purpose of your miles is," says Randy Petersen, the world's leading expert on mileage programs and the founder of WebFlyer.com and FlyerTalk.com. "Let's say your goal is to travel to Hawaii. Make sure you're enrolled in a program that requires the least number of miles to go to Hawaii or that has the most airline partners that fly there. Don't rely on only one carrier."

Determining the best mileage program for you is actually a three-step process, says Gary Leff, who writes FlyerTalk's View from the Wing blog and recently founded BookYourAward.com, an award concierge of sorts. First, look at the route maps of the airline you're currently collecting most of your miles with and its international partners and see whether they fly to the places you have in mind.

Second, consider how expensive your program's awards are for where you want to go. "If you want to fly business-class to Paris," says Leff, "it'll cost 80,000 miles on Air Canada's Aeroplan but 105,000 on United or Continental." (You don't need to fly Air Canada to collect miles in its program or to redeem them for a free trip—you can earn them by flying any Star Alliance airline.)

Third, factor in how generous—or stingy—your program is with award seats. US Airways, for instance, gives away only 3.9 percent of its seats, Petersen points out, whereas American gives away 9.7 percent. To find out how generous a carrier is, check InsideFlyer.com, which every April reports the percentage of seats each airline gave away during the previous year (search for "award patrol"). Another way is to compare programs using WebFlyer.com's Head2Head tool. Leff says that, in his experience helping travelers redeem their miles for premium-class international awards, it's toughest with Delta and its SkyTeam partners and easiest with Continental, United, and their Star Alliance partners. "If you want to fly business-class to Africa, you don't want Delta miles," he says.