[header] How to double dip travel rewards [title] Enroll in a frequent flyer program that makes sense for you. [step] The most common type of travel rewards are airline miles. In order to earn the most miles, including in double-dip scenarios, you'll need to join a a frequent flyer program that you will be most able to use. 
For many people, this is simply the program affiliated with whatever airline they fly with most often. [substeps] One factor is proximity to an airline's hub.