How to buy cheap airline ticket

I try to Book 45 to 90 days before for airfare, I also usally deal with the actual air carrier unless it s a Super Deal and few restrictions. I also follow the best days to travel for the outbound. The ticket does not cost more if you talk to a actual agent of the airlines most will help you and unless the travel is immeninent they will suggest days where the airfare is maybe lower if you book the ticket with the agent there will be  fee so only book it with the agent if you can pay the service fee. I use some apps for hotels, yet if you call the hotel directly most will honor the app price for a room, if it's like you need a 8-12 hour room, when you call the hotel see if they have a "Rack Rate" that's usally after  6 to 8 pm for there may have been a cancellation and the hotel makes no money on unfilled rooms. I have been able to look at a airlines schedule for sometimes the website will not let you book the ticket and you must deal with a agent say you find a iteneary on line that meets your criteria, yet it won't let you book it on line, when you call the carrier they my try to route you with differant hours (more), charge you more and have one waiting in airports. I book flights that I am in the air and on the ground for no longer than 3-4 hours just enough time to get to the next gate,grab a snack and hit the air.
my last trip was 18 hours of the 18 I spent maybe 4 on the ground in those lovely comfortable chairs they provide for our comfort.
hope it helps.