Plan ahead. Airlines tend to reserve a select number of seats with discount prices, and these tickets typically sell out quickly. Booking your flight 21 days in advance can increase your chances to nab one of these spots. For international flights, book your flight even earlier, at least 30 days in advance or more.
Be flexible on the days you can travel instead of booking high-travel days like Mondays, Fridays and Sundays. Opt instead for flights during mid-week, such as Tuesdays or Wednesdays, or on Saturday. This also applies to the time of day that you fly. Leisure flights will be cheaper if booked either earlier or later in the day, whereas business routes offer cheaper routes mid-day.
Sign up for email notifications through the different airlines that service your area. Often airlines will send out special rates to a select list, which may or may not make it to your travel agent. This can help you sniff out the lowest last-minute fares possible.
Consider alternative airports and airlines. Some smaller budget airlines have discounted rates when you opt to fly out of or into towns surrounding a major market. This can include Oakland for San Francisco, or Burbank for Los Angeles. They also offer no-frills travel, which can save you money in the long run for amenities you may not need, such as in-flight meals.
Look into connecting flights. Non-stop flights are not always the most economical; many discount fares require at least one stop. Be sure to look at both connecting and nonstop flights to ensure you are getting the best deal.
Use whatever discounts for which you may be eligible. From senior discounts to military discounts, there are several ways you can save money up to and including bereavement and emergency illness fares. Some third-party affiliations, such as a AAA membership, can provide discounts for airfare.
Comparison shop between travel agents, who typically don't charge additional fees for you to use their services, and travel websites like Kayak, Travelocity and Priceline. Also call the airlines directly to see if they can beat the lowest prices you find elsewhere.