While its not the most exciting topic, backing up your data is more important than you think. As more of our lives end up exclusively in digital formats they become more vulnerable to loss, theft, or damage. A good back up strategy is like an insurance policy. Its can be annoying to set up, maybe cost a little money, but in the event you need it, it can be a life saver.

3-2-1

The 3-2-1 rule is pretty simple. Three copies, two of which are local, one is in the cloud. Don't try to put those two local copies on the same drive either! Use two separate hard drives (or other physical media.)

Local copies

For hardware you can use any old external USB drives like my choice, the Western Digital My Passport Portable. I like portable drives because they are built to take a little rough handling so if you drop it, it should be more likely to survive than its desktop counter part. Speed isn't a concern and the built in encryption will prevent the novice snoop from having a look see.

For software I would suggest Acronis True Image on Windows or Carbon Copy Cloner on macOS. These cost a little money but offer great control over how and when your data is backed up. In addition they can backup system drives and offer a bootable backup so you have zero downtime in the case of a complete failure.

Windows File History and macOS FileVault are your free options.

Cloud services

There are two options here. The simplest is something like Backblaze or Crash Plan. Both run silently in the background saving all your data to the cloud. Its great because you don't have to manage software or hardware. Download, pay a few bucks, and instantly gain peace of mind.

The second option is something like a Synology Disk Station or a Drobo. These put you in full control. You have to buy the hardware but there are no monthly fees. The other catch is you need to put this device somewhere other than your primary location. For example, leave it in a family members house or possibly at work (but get IT permission first!)

What do I use?

Western Digital My Passbook Portables (a bunch of them) + Acronis True Image + File History + Windows Backup
Synology Disk Station (2 disk model) connected over network
Backblaze on each computer

I have all drives backed up every 3 hours and retain version history where possible. I also stagger these, so cloud happens when local isn't and the local copies happen one at a time. This means if I mess up a document or have a hardware failure, its likely still around in one of my various back ups.