Choose less crowded days for travel. If you are looking for the cheapest days for travel, please choose Tuesday, Wednesday and Saturday. It is less crowded in these days.
Go on a holiday. The airfare may be raised on holiday weekends, so if you choose the very day of he holiday, it will be much cheaper, such as thanksgiving day.
Changeable in your leaving time. The airfare is much cheaper in early morning or late night, for they are out of the peak time for business travelers. If you want to save money, just avoid the day time for leaving and choose early morning and night.
Consider smaller airports. Usually in smaller airports, there are often some discounts offered for travelers. But if you choose the smaller one, you should focus on its destinations to check whether it has your route.
Do the math.  When you know the price, you should check on the details. For example, check which items the price it offered concludes, If it is just the airfare, may it isn’t cheap, maybe the extra fees such as seat selection, and other entertainment are needed to be payed again. Before you pay the fare, you should have a clear inquisition or detailed check.