Hi jorge,
sometimes it's useful to know about file contents, but the normal user should not think about it.
strategies: I make daily backups from all hard disks. So the maximum lost can be one day's work.
Sometimes I use "save as..." to store the position status with a new number. I always work with position .....001.
During my work I send the position to my client, to ask for details, and he knows the status. In one case, I lost a project, and could recover a rather actual status from my sent email.
Do not delete any project.
There is enough space on the hard disk. Once or twice in a year I compress my finished projects, and push them into an archive folder. This folder is on my hard disk, on my backup hard disk and on CD/DVD.