Hotel room prices also go up quite a bit on weekends due to
Not only does it help to be flexible with dates and destinations but being flexible with the route you take is another way to get a cheap flight. Sometimes it’s cheaper to fly to London and take a budget airline to Amsterdam than to fly direct to Amsterdam. There are so many budget carriers around the world that taking advantage of a good deal to another city and then hopping on a budget flight to your destination is sometimes the best way to go. I had to go to Paris once; the flight was $900 USD, but I could fly to Dublin for $600 and get a $60 flight to Paris. It meant more flying time, but the $240 I saved was worth it.
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.