Flixbus around Europe, any tips?

G'day,

I will be traveling around Europe this late summer, but I will be on budget so instead of interrailing I reckon I'll just do Flixbus instead. Do you guys have any advice for me in regard to Flixbus (book in advance, do directs instead of multiple stops etc.). I heard they're pretty much late all the time and/or huge chance of losing your bags as well?

I would love to hear people's experience on traveling Europe with Flixbus :)