How to Get Cheap Airfare
Timing of the Reservation
There's no perfect timing for a ticket purchase. If you see a great deal, grab it while you can. It might be gone literally in a couple of hours.
Generally the lowest fares are available with at least 14 days (30 for international travel sometimes and 60 days for low-cost) advance purchase and a Saturday stay... and no more than a 30 day stay. In some cases the lowest fares are available right up until the day of departure.
A very frequent question people ask themselves goes something like "My trip to XXX is 5 months away, should I buy my ticket now or wait and see if the price drops?"
Several US airlines have a little-known policy that may allay the fear of losing out on a better deal. If you buy a ticket and notice that the price drops later for the exact same itinerary on the same dates of travel, you can call and the airline will issue a voucher towards a future ticket purchase.
United, Delta, American, Northwest, and USAirways all offer have such a policy for sure. Check with the airline you're considering purchasing from. There's often some fine print, such as Northwest excludes web fares from this, but we've found it to generally work well.
Whenever you purchase a ticket it's a good idea to check whether the fare has dropped even a little as that's a free money towards your next plane trip.
Timing of the Trip
The first thing you can do is to avoid flying during high-season, major holidays and events. The demand is at its highest and so are the prices.
If possible, try to pick light traffic days of the week. For example, Friday and Sunday evening flights tend to be the most expensive and tuesday, wednesday and thursday are usually cheaper. So is Sunday evening. Also, staying overnight on a Saturday can save you money, because then you'll get charged an excursion rate, not a business rate.
If you can adjust your times to fly, you increase your chances of getting a cheap fare. Taking the "red-eye" flight can pay off for your wallet because no one wants to depart at 2 a.m. and arrive at 6 a.m.
Other Advise on Cheap Flights
Use the same airline for both directions. Since round trips are usually about the same as one-way tickets, it doesn't make sense not to.
Ask about airports other than your destination's main airport. Look into secondary airports outside the city or even in a nearby city that is less popular. An hour or two by car/train/bus may payoff huge sometimes.
Join a travel club. If you fly more than twice a year, the price of joining can easily make up for itself in the long run.