How to get Cheap plane tickets?

Hey I wanna get roundtrip plane tickets to Madrid from Boston so what;s the cheapest way to do this what time should I buy them I would be there for 3weeks summer, late June to early July|||look around on travel sites such as http://www.orbitz.com http://www.expedia.com http://www.kayak.com etc. the prices generally tend to be the same. Try to look at the different days of the week. Wednesday tends to be cheaper sometimes. The further in advance, the cheaper although you can get last minute deals but it;s risky. When you find one you want, look on the airlines site and if it is the same price buy it from there instead. Also wait about a month because you can;t buy this far in advance for end of June/early July|||depends on when you;re traveling. if it;s a very near travel date, regardless it;s gonna be very expensive. The best sites to go are orbitz.com, travelocity.com, expedia.com outside of that you;ll end up booking on airlines and not know the airline until after you make the purchase.|||Try Travelocity or Lastminute.com : they usually offer the cheapest deals worldwide (available only for the next +/- 11 months)You find them here: http://www.willgoto.com/1/023798/liens.a… .