Great tips! Very interesting to read about since I'm living in Europe (Belgium). Some things to add:
Low budget airlines:
Use sky scanner (app/website) to find the best deals, planned a round trip in Africa only using this app, was a major success
Another cheap way to get around on train is buy the European rail pass:
https://www.interrail.eu/
1 pass for 30 countries, and you can sleep on certain trains :)
Look for B&B's, they are run by local people who know some money saving tips & tricks.
We have some of the best B&B's in a very affordable price range. Find the best ones on Airbnb (app)
Hitchhiking pro tip as a former scout:
Wear a youth movement uniform and always have something to write on, so people can see clearly where you want to go.
Secret tip:
Make some European steemian friends :)
Save travels !
Thank you so much for your great additional tips @sacrezm! True, skyscanner is another very useful website. I'm just a bit disappointed about skyscanner as it sometimes shows prices on the first page, which are not true at the end. With kayak or kiwi, i didn't have this experience yet. Interrail is also a great way to explore Europe. Just the ticket prices were quite rising in recent years so depending on which countries you wanna go and how much you wanna travel, single tickets might be even cheaper at the end. About hitchhiking: In my experience, it can be useful sometimes to write where you wanna go, but the best experience i had was asking people directly at gas stations where they go and if they wanna give me a lift. I will definitely consider your "Secret tip" for my next travel!!;-)