Tips to get the most out of frequent flier miles

Frequent fliers: this one's for you. Want to know how to make the most of all those miles you're racking up?

Airfarewatchdog.com is a website dedicated entirely to flying and all the prices that come with it. The website's founder says the number one mistake people make is not getting the full value of miles, because they spend them on things that aren't that expensive.

To get more bang for your buck, the site recommends upgrading. You can move from economy to first class in the blink of an eye. Also consider booking a rental car or a hotel room. In some cases, you can get a $500 a night suite for about 50,000 miles. And shop online instead of in those airport stores. A lot of them give you bonus miles for going through their websites.