Full fare, you're going down. Way down.
Especially on green days.
Or when fares drop. 
- Avoid ticket price increases by booking flights at least 21 days before travel.
- Try different combinations of travel dates until you find one that fits your budget.
- Set your alarm clock. Ticket prices are often lower on early morning or late evening flights.
- Call your airline to check the status of your flight before leaving for the airport.
- Leave extra time to clear security. Don't bring wrapped presents.