Are you planning to postpone a trip you’ve booked to Mexico because of the swine flu? By now, you’ve probably heard about airlines waiving fees to change your flight. But do you know how to rebook a flight to make sure you avoid any extra costs?

The waivers issued last week, as the State Department advised Americans to delay travel to Mexico if possible, are not much different from waivers related to bad weather and published regularly throughout the year. They usually allow passengers who have already begun their journey to reschedule their return — and fly back home later, until a storm passes, or earlier, if you happen to be in Mexico right now — without having to pay the normal reissue fee…