I’m not a pro and my first game isn’t ready, but this topic is also really important to me. What I do at moment:
- I always make some backup files of my project.
- After that, I fell more safe and I can delete files I think my game will not use like the “test assets” not used in my game that I make after watching tutorials.
I also delete some of the free assets I dont use, and some of them are really large.