I would recommend sticking with one single airline and travel using that associated global alliance. In the long run, mileage will build up and less chance of miles expiring. When I first started joining FFPs, I was enrolled in just about all the major airline programs and not concentrating my miles in one specific program. As I was not in control of the airline that I was traveling then, miles accumulated in the various programs but not enough to redeem. Then when the FFPs went to expiring miles after x months of dormancy, I started to have a lot of soon to expire miles. All was not loss as I converted the expiring miles to magazine subscriptions.