Vacations are itself such an expensive affair that it is good to cut down as much as you can. One of teh ways is to find cheap air flights.

Be patient and check at various companies before finalizing the deal. Donot get pressurized, because no one company has all the best prices.

Try to travel in midweek instead of the weekends which will definiitely cost you more.And ofcourse as a rule, the earlier you book the cheaper the seat.