To get the best deal on flights, it's best to purchase tickets early, but not too early. The cheapest tickets become available about 4 months before the flight date. It's best to purchase around this time before the limited amount of inexpensive tickets are no longer available. When purchasing, it is a good idea to buy tickets earlier in the week, as that is when sales are usually posted.
Studies have shown that buying a plane ticket on Tuesday at 3 pm is the best way to get the lowest price on airfare.
When you choose to fly will also have an effect on the cost of your ticket. For instance, flying on Wednesday is the cheapest day to fly. And, the first flight of the day is usually the cheapest, which may mean an extremely early flight.