Fly out at the right time. As with most of these search related parameters, turns out what we want the least is what makes the cheapest flight. The earlier your leave on a flight, the cheaper it will be. Red eye flights (in the middle of the night) are by far the cheapest, followed directly by early morning flights. Although you might luck out on a rare evening steal, typically the later in the day you depart, the more expensive your ticket will be.
You're not crazy for thinking that a flight price has changed after searching it a few times in your web browser. Based on the cookies in your browser, flight prices do increase when a particular route is repeatedly searched, as the site wants to scare you into booking the flight quickly before prices get even higher. Always search for flights in incognito or private browsing mode to see the lowest prices.