1. I typically book international flights 3 months in advance, and domestic 2 months in advance for the best pricing. When you decide on a place and dates you can start monitoring the prices for a couple weeks in an incognito browser (see below). - but i have found 9/10 times the first time i search for a flight that's the cheapest.
2. The best days to book are Tuesday & Wednesday.
3. Use an incognito browser or private browsing mode so sites can't track what you're searching for thus inflating prices when searching.
If you're using Google Chrome or Safari go to file -> new incognito window or hit Command/Control, Shift, "N"
For Mozilla Firefox or Internet Explorer, hit Command/Control, Shift, “P”.
4. When flying out of the U.S. I try to fly out of a major city (being from Kansas City, MO)
Los Angeles, New York, Chicago, Seattle & Boston have been the cheapest so far. Atlanta is another major airport you could fly out of, but flights out of Atlanta tend to be more expensive.
5. If you can be flexible on your dates and the days you fly out you'll be able to save money. When I search for flights I click the 'show whole month' option and book that way.
6. When using a site like Skyscanner it's considered 3rd party. I have booked 3rd party before, people freak the f out, but get travel insurance and just breathe, it will be OK. (I've had no problems booking 3rd party, check back in though) BUT if at all possible when you're booking through a site like skyscanner always click the 'book direct through airline' option if it's close to the cheapest. *Sometimes the pricing is off by a couple hundred dollars and it's not worth it.
7. When searching I always start with flying out of NYC (if you're on the West Coast I would start with LA, San Fran & Seattle- East Coast I would look at NYC, Boston, Miami & Atlanta- Midwest I would look at Chicago & then start looking on the coast) directly to my destination and see what search result I get. If i'm not happy with the price I will look at other major cities in near by countries to fly to first (maybe even stay a day or two) and then fly to my destination. Most of the time this will be a cheaper option.
For example, flying from New York to Puglia, Italy (Bari Airport) was going to be $1,100 with different layovers in London, Munich & Frankfurt. So I then searched New York to Rome (a nearby city) and my flight was $283. I decided to stay in Rome for a day and then fly from Rome to Bari $70 one way. It's important to do some trial and error with this so you can get the cheapest flights possible and spend your money where it matters: on food and wine.
9. Fly for free with points (I will touch more on this in my journal entry about travel credit cards) I live in Kansas City, we don't have a lot of direct flights from KCI to other countries, other than Iceland. So when I travel from KCI to New York, Chicago, LA, or Boston I really try to get those flights for free using my points from my travel credit cards.