While many theories exist around booking specifically on a Tuesday to save money, the reality is there is no consistent truth to exactly which days are cheapest to fly. Most of the time it is cheaper to leave on a weekday, though this isn't always the case. Your best strategy is to get a quick visual of prices for a whole month to see what days are cheapest for your specific route. Here's how:
Fly out on the right day. Sure, leaving on a Friday promptly after work or heading on vacation on a Sunday after a relaxing weekend might be ideal, but it turns out these are the absolute worst times to fly. High air traffic on these days means that airlines jack up the prices. Plan your flights so that you depart on a Wednesday if possible, followed by a Tuesday or a Saturday. Mid week departures are the slowest, so carriers know they will have to accept lower costs in order to fill their seats.
Travel agents used to have to do most of the footwork for
Typically, I start all my searches with Momondo because it searches all major AND budget airlines, non-English websites, English websites, and everything in between. I’ve been using them since 2008 and they vet all the sites they link to as they have strict criteria on who the operate with. Momondo is one of the most comprehensive booking sites out there, they have the lowest price 99% of the time, and it’s the search engine all the other travel experts I know use too.
Compare between different airlines (regular and budget) and between the different classes of seats offered! If you can enjoy business class on a budget airline for the same money you'd pay to fly economy on a more "prestigious" airline, more power to you. You end up in the same destination but get to enjoy a more comfortable, luxurious experience. Why not?
Websites are the easiest way to find a good airline ticket
Airline rewards programs are a great way to get free flights, free upgrades, and free companion tickets. No matter how often you fly, you should be signed up for the airline’s reward program. I stick to US-based airlines since they are involved in all the major alliances and you can earn miles on their partner flights. For example, if I fly Singapore Airlines, I can earn United Airlines miles because they are partners. Likewise, if I fly Air France, it’s credited to my Delta rewards account.
In Google Chrome or Safari, incognito is enabled by hitting Command (or “Control” if using PC), Shift, “N”. For Mozilla Firefox or Internet Explorer, hit Command (or “Control” if using a PC), Shift, “P”. This will open a new browser window where your information is not tracked, thus not inflating prices as you search. Note: if you're using an older version of OS X, open Safari then click “Safari” in the menu bar, and select “Private Browsing”.