Firstly, it depends how much you've got to back up and how often it changes.
If it's mostly photos, emails and messages then by far the simplest method is just using icloud.
It'll do everything for you automatically and it isn't that expensive. I think it's even still free up to a certain limit
But on top of that I back up docs and photos once in a while to an external drive depending on how much new stuff I've created and I keep it simple. Mac OS has something called 'Versions' as well so it will autosave and also keep previous versions of the document on the machine you can go back to.
I use exFat as the drive format and simple drag and drop. (And it should be exFat rather than FAT32 because FAT32 doesn't handle big drives well if at all).
It's really not a big deal to do this even daily because with a cheap SSD it will transfer a ton of data really fast.
The really big SSD are quite expensive so check the best price point because 2 or 3 smaller drives may well be much cheaper and give you better protection (as they won't all fail at once).
The spinning HD are even cheaper and just take a bit longer which isn't a problem with a bit of planning. You don't have to stand over them
A combination of icloud and the occasional back up is probably enough especially if you take the 'little and often' approach.
I backed up my wife's icloud photos to an SSD the other day and I think it backed up about 6000 photos and videos in about 15 minutes.
There is a huge advantage to doing it this way because your files will be saved individually and be readable by just about anything including a Windows machine.
When you use Time machine- or most other backups- they create a file called a 'sparse bundle' which lumps everything together and is only readable by that program.
Great as long as it works but if you have a problem with it and then need to extract something it's utterly useless.
And that does happen especially when you most need it because if your machine is dead you have to create an identical user ID on the new machine otherwise you won't have permission to read anything (unless it's changed in the last few years of course but I doubt it). I've had that happen.
So for maximum protection, save it in a format everything can read and where you can find what you need when you need it.
Also you asked a question about SSD. They are way more reliable than spinning HD which can die in as little as 2 years or just by turning the power off.
They are pretty much the same as the little SD cards which are indestructible (We've had them go through the wash and my son used one as a gardening implement)
Don't get hung about it and keep it simple as at least one other person has said.
