Who hasn't experienced it before. Suddenly you can no longer find important data that you need.
Whether accidentally deleted, whether there is a hard drive defect or an encryption virus is responsible, we would be happy to have made a backup now.

How it is backed up is initially unimportant, the most important point is to decide what is worth backing up at all. The approach I recommend is to back up everything, whether it seems important or not. If you are only able to back up data that has changed since the last backup, the backup duration is important only for the first backup. If it turns out that certain data does not explicitly need to be backed up, it should be excluded. An example of this is the directories C:\Windows\Temp (Windows) or /tmp/ (Linux).

Various tools are available under Windows that also allow incremental backups. Personally, I use SyncBackSE, but other tools can certainly be used as well.
With Linux I use „rsnapshot“, which enables backups as a hierarchy. For example, rsnapshot can be configured to keep 7 daily, 5 weekly, and 3 monthly backups. Rsnapshot works with hard links and does not waste space on the backup medium for duplicate backups. The underlying tool in the background is rsync.

On the one hand, it is important that the backup medium is also able to save the metadata (access rights, etc.). For example, an exFat drive cannot store NTFS rights. So choose a medium that can store all data and metadata.
USB drives are also ideal for backup, as is a home NAS.
Note: No matter what medium you use, it should only be connected to the PC during the backup. For example, if you leave a USB drive plugged in, an encryption virus will not stop there. The same applies to network drives that are connected or whose credentials (user/password) have been saved for convenience. NAS drives also have security vulnerabilities and in my view a USB drive is preferable because no virus in the world can plug in a cable into the PC.

As mentioned at the beginning, the backup is only the means to enable data recovery. A restore of the data must be tested and the result verified. This should be done periodically, because our backup program also receives updates.

Take data backup seriously. If you don't have a backup, you deserve no sympathy. I consider all data that is not contained in a backup to be unimportant.
You can fix broken things after they break, but lost data is just that: Lost