1. Use Search Engines for Flights
Powerful tools I personally use to find my flight tickets:
Always check airfares on more than one search engine. You can also check the price on the official airline website.
Ticketing prices have strange behaviour. Return trip flights are sometimes cheaper than single trips, booking the stretches in 2 different bookings are sometimes cheaper, and so on. Most of these anomalies are detected by Google Flights, that’s why it is the most powerful one.
Google Flights is very useful to find the cheapest days in a month.
Adding multiple airports to your search is another big advantage of Google Flights. Here’s an example if you want to go to Thailand. Domestic flights are very cheap in Thailand so it doesn’t matter where you arrive in Thailand. The airport codes were set for Pattaya, Krabi, Bangkok, Chiang Mai and Phuket (max. only 5 airports per search). You can use World Airport Codes tool to find airports in a certain country or city.
2. Look for deals and promotions
A lot of websites list promotion deals. My favourite updated list is Premium Deals on Flyertalk Forum but economy flight deals are also listed on Flyertalk Forum. I also use Fly4Free find error fares. For UK and EU based travellers, you can check HolidayPirates too.