Saving after every complicated edit and before every break is a minimum. A
routine of 4 saves an hour is sensible. Files are fairly small so just number
them in sequence. You can tidy up later. But if you decide you have accidentally
deleted something or made a complete mess of the last edit, you can go back one
step. Much software give you an undo but when the failure of either one can be
disastrous it is always best to hold your pants up with belt and braces.
If you change your mind later there is always something to go back to. Late
nights and looming deadlines make for trouble. You can be so much braver if you
know there is a safety net.