Here are some of my non-trivial tricks for a cheaper ticket search. They work with most flight search engines and hotel booking sites as well.

Best time to buy

Tuesday after 3 pm.

Why: Big airlines statistically tend to announce discounts around that time.

Price discrimination

Many travel meta-search engines and flight search engines play dirty with us.

They modify the price based on our search history, location, and demography.

Tricks

It is good to know some of the tricks they use:

1) Price can go up while you search for the ticket.  Sometimes it is even visible if you press F5 refresh key on your browser. Sometimes every time you return to the site to search for tickets, the price goes up.

Solution: after several days of search, when you’ve made your final purchase decision, go to your Chrome browser incognito mode and make a purchase from there.

2) Country specific price markup. Looking for tickets from rich countries? – get a higher price.

Solution: use VPN with a Germany IP since Germany is known for a very rational spending habits.

3) Apple device specific price markup. Sometimes if you use Apple devices, you can get an invisible price markup.

Solution: Use Windows or Linux devices for a purchase, if possible

Other tips

It is sometimes cheaper to buy discounted air carriers tickets directly on the airline website. One of the reasons for that is that you often can get a promo code on the site main page that you would miss if you buy from flight aggregator.

Some websites can implement a tactic of showing the final ticket price slightly higher than it was shown in a search. The difference is so small (several dollars) that most of us will never realize it.