I'll share my strategy. Not for the novice I must say. But if you know a bit of disk storage and backup technology, I think you should be able to follow along.
I assume your data is online somewhere in your desktop/laptop. I use a backup software to backup to 2 places, 1) an external multi-bay enclosure and 2) google cloud. Backup software used : Duplicati. It is a full fledged open source backup solution. It can do versioning, which is critical for me. It can also make use of VSS to backup open files, but with caveats of course.
On the external multi-bay enclosure, I use a software call StableBit DrivePool. I configure it to pool the diskspace from my external enclosure into a logical volume. I have 4x 4TB Ironwolf, so I'll see a 16TB disk device. The nice thing about this is that I can create a folder on the pooled device and specify that every file inside that folder will have X copies of it stored in the underlying 4x 4TB Ironwolf. X = 2 in my case. So if I put a file called VeryImpt.Doc inside this folder, I'll be able to find this file physically stored on 2 of the IronWolf. With this in place, I actually have 3 copies of my files, 2 in the IronWolf and 1 in the cloud (I use GDrive). The other nice thing is your HDDs need not be the same size, I once had 2x 2TB, 1x 3TB and 1x 4TB before I upgraded them seamlessly to 4x 4TB IronWolf. If you use a typical NAS/Raid, you need to use all of the same size.
I have never lost a single file through this strategy. I have lost many HDDs but DrivePool have worked like a charm and recovered everything.