Unless you are planning travel for high-traffic days, like Christmas or July 4th, you stand the best chance of finding the lowest possible airfare 45 days out for domestic flights and 60 days out for international flights. You will seldom find or get a better price searching or booking any earlier.
Flying midweek is another easy way to save money – and find more available seats at cheaper prices. Booking is often busier right after paydays on the 1st and 15th – so try traveling after the 7th of the month.
After shopping for fares online, clear your cookies – or better yet, book on another computer (from a different location, if possible). Airlines track online behavior, including IP addresses, and prices could go up for flights that are searched frequently.
Better than booking online is often calling airlines direct and speaking to a live human – ideally at 1:00am on a Wednesday night (on hour after Tuesday midnight in the time zone where the airline is based). Most low airfares seem to appear between Sunday night and Monday night – with 24 hours for those who reserve those fares to pay for them. At midnight Tuesday, all unpurchased discount fares are usually released back into the airline’s computer system – giving you greater opportunity of getting one of them.