I save very often. This is something I used to do when I was playing The Sims 2, and I've been doing the same with TS4. Lately, I've been having some issues with my computer: occasionally my game crashes, so then I lose progress. So now I'm saving even more frequently to try to minimize the possible loss of progress. The crashing usually happens when I'm finishing gaming session and exiting the game (luckily it doesn't happen each time; it happens occasionally) - but I have a habit of always using the "Save" -option and after that choosing the "Exit" -option; I never use the "Save & Exit" -option, so usually in this case when it crashes, my progress is saved. But the game has also been occasionally crashing randomly during gameplay or while I'm in Build Mode building, so I'm now even more cautious and I save very frequently. (I don't use any mods or CC, I play vanilla). (I need to take my computer in for service to check what is causing the problems).
I do also regularly back up my Saves-, Tray- and Screenshots folders, and I keep those back ups in a separate memory stick, so that I have my game safe and stored, in case my computer breaks, or something.
