If you want to save your complete install in a reinstallable way as an image, look at Clonezilla. For just a backup you could simply use cp -a.
What a fun topic! It's one of the big interests I've had to acquire in the 3 years since I started using linux. <g>
I've never used Clonezilla. I did use Ghost's predecessor, Partition Magic, when I was still entrapped in Windows. It's a lot faster just to use dd onto some empty drive if you ask me, and even that takes far too long.
Backups are only useful if you actually do them. If you don't do them, at least as frequently as you make significant progress, you might as well not bother. Murphy *is* out there, and the minute something can go wrong, it *will* go wrong.
The cp alternative is faster, since it only copies the space-in-use instead of the whole partition. But it still takes too long. On the other hand, rsync can be used to copy only what needs to be backed up. IF you can figure out which options to give it, and IF you've installed it (few distros install it by default <hint>).
But even if you've stashed a backup partition that's an exact duplicate of your data (in this case, your "install", but an install is just data), you have the issue of setting up the right kind of partition table and copying your backup partitions into it, and then setting up a boot-loader, preferrably one that works on both BIOS and EFI systems.
It is not trivial if done right; I did it wrong a couple years ago since I'd never heard of GPT or EFI at that point, so now I'm being allowed to modify/rewrite to do it better. Forget "right", they haven't defined that for us yet. <G>
So I struggle along, but I do have an sd-card that fits in a USB adapter, that is bootable, and contains Ubuntu-oneric, Debian-wheezy, and Debian-stretch, along with all of the data I've been building since maybe 1992 when I left the mainframe world. And with that I can, in an hour or so, restore 2 of my three systems onto a new or wiped drive, and be just where I was before things went south.
Which reminds me that I should get back to reading the EFI Spec instead of yacking in forums, because my 3rd system is an EFI-only system and won't even recognize my rescue stick as bootable. To quote my wife, "software is never done!"