I make a backup of any data or configuration file I remember changing. I'll also make a backup snapshot of data or configuration files if I'm making a lot of changes. The snapshot backups are in case I mess something up and don't notice it.
I always append the date and a sequential number, and the computer model (I use two computers) to the end of my files. That way, I know when the file was backed up and from what computer. For example:
my--spreadsheet--file_20190504-01_xyz123.ods
