I'd like to get some advice from the readers of this board on how they play the airfare game.

Next May I'm planning on flying from either BOS or JFK/EWR to London (LHR) and then taking the train to Scotland. Today for nonstop flights (my preference) prices range from $918 (Kuwait Air) to around $1200 for AA, DL, BA,& Virgin. I know that prices change from minute to minute, but are there better times to lock in a decent price? How long would most of you wait to get the fare you want without jeopardizing getting to your destination without bankrupting yourself. If Kuwait's flight is the best that I can find online, will other airlines match their fare?

Any tips - or sites for tips - would be greatly appreciated.