Watch Airfare Trends
Spend a few weeks checking airfares to the city you want to travel to. Get a feel for what is a normal price so that you will be able to recognize a good deal when you see it. If I have a destination in mind, I try to do a quick airfare check each day for a week or two to see what pricing trends I can recognize. If your dates are at all flexible, play with different days of the week. Tuesday, Wednesday, and Saturday are usually better days to find cheap airline tickets.

Book Airline Tickets Far in Advance
Generally speaking, the earlier you can buy your ticket the better. And I mean a whole year in advance when possible. I know there are those random last-minute deals, but when you need several tickets for a family, it is unlikely you will find a cheap last-minute flight. Especially if you want to travel around Christmas, the day the tickets go on sale one year in advance is often the best date to buy.

Search Airports in Nearby Cities
The cost of airfare can vary between airports. If possible, consider alternative airports from your hometown or into your destination. You may spend a little more time in the car, but when purchasing tickets for a family, you could save hundreds of dollars if you are willing to drive an extra hour or two.

Compare Hidden Fees Before Booking
Cost-saving measures in the airline industry have made it so every airline has a different fee structure. Will you be paying for your bags? Drinks? Extra legroom? Carry-on luggage? It seems that just about everything has a price tag, but that varies from airline to airline. Some discount airlines are notoriously bad for trying to hook you in with a super cheap deal but then charging you for everything from your carry-on bag to the right to pick your seat. Make sure you are comparing apples to apples when you decide what a good deal is.