The 3 best types of flight deals that will save you a ton -- and how to spot them

John Loo/Flickr It's a lot easier to find cheap flights if you know where to look and how to find the best deals. First, make sure you keep an eye out for flash deals, in which airlines sell a limited number of heavily discounted seats. Airlines will also lower prices when they are forced to compete with other carriers over the same routes. Mistake fares are ridiculously cheap tickets that briefly appear because of a misprint or data entry error — but your tickets may be canceled after you boo...