3. Search for fares throughout the day, several times a day.
Fares go up and go down throughout the day like the stock market, so if you don't like what you see at 10 AM, come back a couple of hours later and search again. Just as important as the fare, seat availability can change throughout the day. Airlines adjust the number of seats available at different fare levels, so even if the fare hasn't changed, the availability of seats at that fare may fluctuate, so you'll see a $120 fare one minute, but the next it's gone. Obviously, seats at the lowest fares sell quickly and in 2009 airlines will offer fewer seats at the lowest fares. If you see something good, grab it.
See tip 4.