Book as far in advance as possible to up your chances of getting your choice of flights.
What began as a way to reward customer loyalty has evolved into a profitable side business for the airlines, who sell "award miles" to credit card and other companies (who pass along those miles as incentives to their own customers). Here are some strategies for getting the most travel out of your miles. For more tips, check out www.flyertalk.com.
Book as far ahead as possible. Airlines reserve only a handful of "award seats" on each flight -- and once they're gone, they're gone. Even if the "award seats" are booked up, you can sometimes use additional miles to get on the flight (for a first-class seat, or for a double-miles "rule-buster" seat -- though these are being phased out). In short: The farther ahead you book (ideally several months in advance), the more likely you'll get your choice of flights for the fewest miles.
Maximize the miles you earn. I'd never fly on a particular airline just to get the miles. For me, the price and convenience of a flight plan always trumps the potential for netting miles. But if you're flying anyway, many figure you might as well get all the miles you can. For example, booking direct with the airline, rather than on a third-party booking site, might earn you bonus miles. Some credit cards allow you to accrue miles with each purchase (sometimes with an annual fee).
Know about alliances. Most major airlines belong to one of three gigantic frequent-flier collectives. For example, the Star Alliance includes North American airlines (United, US Airways, Air Canada) as well as European carriers both big (Germany's Lufthansa, SAS Scandinavian, LOT Polish Airlines, Spainair) and small (TAP Air Portugal, Croatia Airlines, Slovenia's Adria Airways). Other alliances include SkyTeam (Northwest, Continental, Delta, KLM, Air France, Alitalia, Czech Airlines) and OneWorld (American Airlines, British Airways, Air Iberia, Finnair, Malev Hungarian).
If you have miles on any airline in the alliance, you can redeem them on any of the others. So, for example, if you're headed to Prague, try using your Northwest miles first (allied with Czech Airlines); for Helsinki, see what you can get with your American miles (partnered with Finnair); and for Croatia, check with United (allied with Croatia Airlines).
Use airline alliances to collect miles smartly. The same alliances work for collecting miles. You might not care about earning miles for an SAS or Air Portugal flight, but if you give them your United frequent-flier number, the miles go into your United pot.
To redeem your miles, check online first, then call. Check if the flight you want is available on the airline's "miles redemption" site. If not, don't give up. Call to speak with an airline agent. While this can come with a small additional fee, it's worth it to talk with a live person who has all your options at his or her fingertips -- especially if you...
You're still responsible for taxes and some fees, but it's still a fraction of the full fare. If airline miles help you afford to fly, using them smartly can help you actually fly more frequently. Happy travels!