Pick the right days of the week More often than not you will run into day and time restrictions. Essentially, this means that some days of the week are cheaper than others. These days of the week change every so often. Currently, for most airlines, it's cheapest to fly on Tuesday, Wednesday and Saturday. Avoid holidays Traveling during the holidays is notoriously expensive.
Most airlines have black-out days around popular holidays.
Not only are the fares more expensive, but often you cannot use frequent flyer miles during these periods either. Flying on the day of a major holiday can sometimes be a way around poor availability and expensive fares. Make sure that you are registered with the frequent flyer program of any airline that you fly. When making reservations, keep in mind that it may be a better idea in the long run to consistently fly with the same airline and accumulate frequent flier miles, than to base your criteria strictly on which carrier has the lowest fare.