You could put your project into a version control system (like git). There are several free services (like GitHub or Bitbucket) available out there. You can also set it up locally so that it’s only saved on your computer. This will enable you to basically have backups so you can restore different versions of your scene. And if you accidentally delete something you can restore it as well. It also removes the fear of “doing something wrong and not being able to revert it”.
Anyways, I’m also starting to create a Sci-Fi scene so I’ll be watching this thread. Good luck. 