Let me share my exact process for finding cheap flights, because 'be flexible' is the advice everyone gives and nobody explains how to actually implement.

Step 1: Figure out your actual flexibility. Can you leave on a Tuesday vs a Saturday? Can you go 3 days earlier or later? Can you fly into a secondary airport? Every one of these opens price options.

Step 2: Use the Google Flights date grid. Enter your origin and destination, go to the calendar view, and look at the full month spread. The cheapest date is usually midweek in a non-peak month. The variation between the cheapest and most expensive date on the same route is often $100-200.

Step 3: Check connecting flights manually. Google Flights and Kayak both show connecting options but they sometimes miss cheap routings. Specifically: for transatlantic flights, flying via a budget European hub (Keflavik, Lisbon, Madrid) on one carrier and then onward on a separate ticket can beat the direct price.

Step 4: Set price alerts and check back weekly. Prices on a route 6 months out are rarely the final price. I usually see 2-3 significant price drops in the 6 months before a flight, with the cheapest sometimes appearing 6-8 weeks before departure.

Step 5: For error fares, speed matters. Sign up for Scott's Cheap Flights, check it when you get the alert, and have your passport number and a card ready. Error fares sell out in hours.