That's exactly how I've tended to do it in the past. I've zipped all my saves and snapshots into a backup archive every day (takes about 30 seconds). And store that on a separate hard drive.
Of course you can also just create a new save file every time you save manually in game (now). So I increment the letter appended to the end of the save file name every couple of missions, when I'm recording a playthrough. This protects against me making major cock-ups too, as well as rare bugs that might effectively corrupt a save.
(9) Upload snapshots, save games and log files - on Windows 10 the file directory for save files and snapshots is:
Uploading some of these can be extremely helpful for the devs to see and reproduce bugs.
If the game crashes out (without locking up too badly), it should create a crash dump folder, named by date and time, containing an "crash.dmp" and "error.log" file. In the following location:
Please Zip the appropriate crash folder and drag-drop it onto the post you are writing, to attach it.
Even if the game doesn't crash or make a crash folder, the "output_log.txt" contains helpful telemetry data for the devs. It is wiped and overwritten each time you re-start the game.
Or see the 0.8.1 patch notes for Mac and Linux directories:
Previously the game stored everything in it's route Steam data folder:
e.g. "C:\Steam\steamapps\common\TerraTech Beta"