In Central America you can add Volaris and Internet sometimes has better deals than them. Just need to monitor everything. You can set up notifications in sky scanner app for example, or push notifications on fly4free.com Other than that I always look for tickets on Mondays, there are more deals. Try to fly out of high season, like January, you can get deals for 200-300$ from Europe to South America or Asia. Check charter flights operators like TUI, they have sometimes deals for 100€ return to many destinations and offer food and drinks. I'm looking at airports websites to check new, small airlines, which are not included into apps like kayak and found great deal as well, like 350$ Cancun - Rome with 787 dreamliner, airline called Neo Spa. I think that's all tips I would add :)