3. Compare Prices Online
Several great comparison sites help you find the best tickets. The AARP Travel Center powered by Expedia aggregates most airlines and prices, and you can narrow your search according to date flexibility, number of stops and so on. Kayak is particularly good as an aggregator of airline fare sites. It will open several windows to show you what Expedia, Priceline and others offer. Once you know these prices, check the airline websites; occasionally, airlines have sales they don't post on comparison sites. Also, check the sites of discount airlines like Southwest, jetBlue and RyanAir, whose fares aren't necessarily included on comparison sites. Finally, be sure each quoted fare includes taxes and fees, and read the small print on any "sale" price for your ticket.

4. Track Airfares
So, will you get the best deal now, or should you wait a few days? To find out when to buy airline tickets and save money, check out the fare-casting and fare-tracking services on sites such as Bing Travel, Orbitz, Airfare Watch Dog, Fare Compare or Yapta.

5. Join Frequent-Flyer Programs
Go online and sign up for frequent-flyer programs with all the airlines that fly to your favorite destinations. It's free, and the miles do add up. Just remember that there are blackout dates for using your miles, and some programs charge a fee to "cash" them in.

Also of interest: 

• 5 tips for getting deals on holiday flights.
• Slideshow: 10 super easy ways to spend less money.
• See the AARP home page for deals, savings tips, trivia and more.