FF-flyers Guerilla-tip #NNN ("how to beat the system"): One of my friends says:
"Buy full fare (one year valid, exchangable, returnable) flight-tickets with a (mileage-program) credit-card, then just AFTER cashing in all your miles and just BEFORE giving up that credit-card (best Diners and/or American Express), return the tickets and let them be fully credited to your credit-card-account."