Q. I'm not a frequent flyer so I don't know how these miles work. I understand that if I don't use them then they could expire, and I'd hate to lose them before I even have enough to put towards a trip. I thought I read somewhere that you can do something to keep those miles from expiring. Any ideas?

A. Most frequent flyer programs will expire your miles if there is no "activity" in your account over a 12, 18 or 24 month period depending on airline (Delta uses a 24 month limit, JetBlue and Air Canada a 12 month limit). In our opinion, the best way to preserve frequent flyer miles, other than flying of course, is to buy something, anything, online using the airline's shopping mall. Not only do you preserve miles, but you get extra bonus points as well. Most all airline have relationships with online retailers, such as Apple, Target, Sears, and Walmart and when you buy through the airline's mall web site you'll get between 1 and 10 frequent flyer miles for each dollar spent, even if it's just a $1.49 iTunes purchase. You can also sign up for and use an airline-affiliated credit card, which counts as account activity, but these can have hefty annual fees. More on this, and links to the airlines' mall sites, in the Airfarewatchdog Blog.