Q. I'm trying to find a good deal from Hartford to Miami this fall. Do rates change daily? Should I search for fares every day? If I book today, how can I be sure that I've gotten the best deal?

A. Airfares are a lot like the stock market. Prices change up to 3 times a day on domestic routes, and even more frequently on international fares, depending on demand and the whims of the airlines. It's anything but predictable. We do recommend checking Airfarewatchdog (and other fare monitoring sites such as Yapta.com, Orbitz.com, Farecast.com, and Farecompare.com) everyday to keep track of what's being offered. A good way to know that you're getting a good deal is to sign up for Airfarewatchdog alerts for your preferred route and when a great fare becomes available, you'll get an email notification.

If you're jittery about buying too soon, and find that fares have gone down since your purchase, call your airline. Many will offer to refund the difference in the form of a travel voucher valid for one year, as long as you remain on the same flight and travel dates, but they usually deduct a "service" fee (up to $150 on domestic flights, and $250 or more on international ones) that may wipe out your refund. Three airlines, however, will refund your fare drop without a fee: Alaska, JetBlue, and Southwest. Yapta will allow you to register your flight and fare, and alert you if you're entitled to a fare drop refund, but it only works with certain airlines. However, the best strategy is to buy when the fare is low rather than go begging for a refund.