Use the right site to find the best fares, be flexible and continue to monitor prices after you book. By the editors of Kiplinger's Personal Finance From Kiplinger's Personal Finance, April 2014 Step 1 Go to Kayak.com/flights and enter your departure city, destination and travel dates. The tool scours travel and airline sites for the best fares. (Kayak doesn’t include fares from Southwest Airlines, so you’ll have to visit Southwest.com separately.) If enough data is available, the “Price Trend” feature lets you know whether to buy a ticket now or wait for a potential price drop.See Also: Ways to Avoid Airline Fees Sponsored Content Step 2 If your plans are flexible, try testing different dates and airports. You may save money by flying on a Tuesday, Wednesday or Saturday afternoon or out of a satellite airport. At Airfarewatchdog.com, you can sign up to get e-mail alerts when low fares pop up on routes you choose. You can also subscribe to e-mail alerts directly from the airlines. Step 3 After you book a flight, continue to monitor prices. A federal rule allows you to change or cancel a flight without charge within 24 hours of booking it. Even if you find a better price after a day has passed, you may be able to rebook your flight and get a refund for the difference from the airline. And at Yapta.com, you can enter your flight information to get e-mail notifications if prices for nine airlines sink enough to outweigh any change fees. The payoff You’ll save money and beat the airlines at their own game.