I have two external CHDs, 2 TB each connected via USB 3. On my Windows 7 desktop I use the still viable (but no longer commercially available through Symantec. You can still buy it via Amazon though.) Norton Ghost 15. Since Ghost doesn't work with Windows 8 and 10 which I have on another desktop, I use Easeus Todo Backup Free which works about as well as Ghost and is completely free for home use. I have another two USB 3 connected CHDs on that system. With both Ghost and Easeus, I just set them up and they perform backups at the intervals I want. On my most important computer it's automatically backed up every 4 hours with 6 generations of full system backups to a different drive. Periodically I copy my most important data to a flash drive which I keep in the glove compartment of my car. Once every 6 mos. or so, I make another copy of my data and take it to my safe deposit box at my bank.
The above might sound like a lot, but most of it is totally automatic, taking no time or effort on my part.