I need ways to keep my Airline miles from expiring
In the past I have done things like go to certain websites and watched "informercials" to get 250 miles posted into my account. This would keep miles from expiring for 18 months or 3 years. Is there a list or website somewhere of things to do to keep my miles from expiring?
I need to keep my Northwest, Delta, United, and American accounts from expiring.