Agree with all above. If you have time, learning a version control system (a.k.a. VCS) like Git is really helpful for any sort of development. The first step is to understand the very simple basic principle -- it's save points for game dev. Treat it like that to start with. You figure something out and are happy with the state of your project, "commit" (a.k.a. save the game!). Ever do something and think "oh no, it's all gone wrong!", you can simply "revert" (reload from save point). Truthfully it's a *lot* more powerful than this description but if you start with that basis, you're well on your way to gaining most of the benefit.
One tiny addendum to all of this is that Unity creates a lot of extra junk. In or out of VCS, it will just regenerate it if it's not present. As such, we never commit that stuff to VCS. You tell Git what to 'skip' saving (since Unity will rebuild it) by having a simple text file called ".gitignore" next to the ".git" directory (where Git stores all its save points). Google online to find one for Unity and when you want to save your game, it'll keep the list of stuff that's changed much smaller (and thus easier to read and use less space!).
HTH and GL! :)