When air travel declined in September, airlines began offering extra frequent flyer miles to encourage business. And last week, some airlines liberalized the rules for claiming award tickets. But is it all good news? Not necessarily, says our Savvy Traveler, Rudy Maxa.

Oh, sure it's been raining miles the last few months. Until the end of last year, almost anyone who pre-registered with an airline could earn double miles for flying. And until March 20th, you can still collect double miles aboard US Airways and Delta as long as you've pre-registered at the airlines' Web sites.

Then things seemed to get even better with Northwest's announcement that it was eliminating blackout dates for award tickets. Those dates usually straddle the most popular times for flying, like the Christmas holidays. Several other airlines followed suit. Now, those kinds of decisions are trumpeted by airlines. But they don't go out of their way to publicize increases in the number of miles you need to claim a free ticket. Northwest and Continental, for example, both quietly raised the number of miles needed for a domestic ticket from 20,000 to 25,000. And unlike the competition, you still have to stay over a Saturday night to get that -- otherwise, be prepared to cough up 50,000 miles.

It's time to change a few things in my never-ending course on maximizing miles.

See, airlines are trying to deal with mileage inflation. In the year 2000, according to WebFlyer.com, flyers earned 12 percent more miles than the previous year, but the number of miles redeemed actually fell by a couple percent. So what happens when you have inflation? Prices usually go up -- which is one reason why, beginning in May, Alaska Airlines' passengers will have to fork over 10,000 miles for an upgrade, instead of the current 5,000.

So what do you do? Well, you have to get better at the game, too. Here's my most important tip of the day: Make a habit of checking out the Web site of the airlines you fly most. The other day I browsed the Continental Web site and learned I could convert American Express Membership Points -- earned when I use my Amex card -- into Continental miles at a 25 percent premium through mid-March. If I happened to be flying the airline's new nonstop flight between Houston and Amsterdam, I could earn 4,000 extra miles -- if, of course, I knew to register before traveling.

At Delta's site, I learned if I booked an award ticket on line, I could save 5,000 miles on domestic coach and business class tickets, as well as on free tickets to Central and South America. I could save 10,000 miles on award tickets to Europe. Most of those offers, by the way, expire toward the end of March.

Now, don't get your hopes up when you hear blackout dates have been eliminated. Those are still the most popular times for flying, so if you want to snare an award ticket, you'd best plan way ahead. If you have your eye on a free ticket between the U.S. and Europe this summer, for example, you should pick up the phone just as soon as this show ends and begin shopping for available dates.

There is such a thing as a free ticket. But today that requires cunning and constant vigilance. From the Savvy Traveler, I'm Rudy Maxa for Marketplace.