Usually, I figure out when and where I want to go and then check travelocity.com for fares in a general time period between the two cities. If I see something really good, I'll go to that airline's website and buy the ticket there, as Travelocity, orbitz, etc have a markup of like $10.
Other strategies include signing up for special fare alert emails on airline websites. Just recently, I got an email from Lufthansa advertising the new CLT
service in the spring and introductory fares for $199 roundtrip. I ended up buying tix for me and a friend on Lufthansa.com. If I didnt get that email, I wouldn't be going to Germany in May.
I don't use studentuniverse or STA
travel due to the lack of scope they give in terms of fares. The prices don't change too often, and you have to have one of those stupid Student ID
cards they sell.
Just keeping a watch on fares between certain cities gives you an idea of what to expect, depending on the season and other factors. Florida is expensive in the winter while Europe is cheap. Delta pretty much matches the fare to any city AirTran serves, etc. Gotta know your markets and what influences them.
Also- be patient and wait for sales to come around. They always do. Never pay full price for anything.
Maintain thine airspeed, lest the Earth rise up and smite thee.