Book your tickets early or just a few days before departure. The best deals are available 21-45 days in advance. Or wait until two to three days before the trip when you can buy the unsold seats at a steep discount. Avoid the week before and after holidays.
Time your trip for the lowest fares. Midweek flights will be the cheapest. Avoid flying during the pricier weekends.
Compromise on your flight plans. The more flexible you are, the more money you will save. Be willing to accept alternative departure times. Book flights with layovers because they are much less expensive than non-stop flights.