I also don't trust auto-backups either...I prefer to do them myself.
Same here, I use a very simple method. Simply attach an external with enough free space, and in the Home folder, there's several main ones with content. Simply drag & drop these to an external once weekly, and I prefer to keep the last two copies, and rotate externals for this task. Will use one on one week & another on the following, that's not placing all of one's eggs in the same basket. Plus am signed into Firefox & Google Chrome, so my bookmarks will be where I left these.
Thing is, the OS & most all of the software & customizations can be restored in hours, making the OS disposable if broken, the user data is what needs to be protected.
The other alternative is to Clone the OS HDD to an equal size HDD with Macrium Reflex...I've done this in Windows many times but not in Linux
I've successfully cloned Linux Mint 17.3 * 18 with Macrium Reflect three times, one time from HDD to SSD, the others where swapping SSD's, as the 120-128GiB sizes are no longer relevant, as 250-500GiB sizes has became the norm, and I have as of this posting, two unused 120GiB Samsung 120GiB SSD's. These are great for Linux installs, especially if one doesn't have too large of a /home partition (24GiB root, 1GiB Swap & 80GiB /home (this leaves just the right amount of unformatted space at the right end for overprovisioning). Even though root doesn't use a lot of space, it's important to keep free space on a SSD, the closer to under 60% full, the better. Any more, the controllers has to work hard to keep the drive clean & fast. If too full (over 80%), the SSD speeds will choke, and may not be too much faster than a fast SATA-3 HDD running at 7200 rpm with a 64MB cache.
Also, while on the subject, have successfully restored a backup image of Linux Mint 18 taken with the WinPE media of Macrium Reflect. Unlike some 'Linux only' backup solutions that requires a sector to sector backup image, Macrium uses a method that compacts the data, while keeping the partition structure in place, making a 100GiB total install only use roughly 30GiB on the backup drive. And as an added bonus, the restore (as well as the backup) will be much faster than say, a Windows backup/recovery/clone operation. Don't ask me why, because I don't know, though I find it odd that these tools created for Windows actually works faster on Linux images & cloning. The speed of the restore is like a madman in action, it's shocking to see how fast these restores (even on USB 2.0 or eSATA).
While I know that others has other ideas that didn't work for me, maybe because on my PC's, I install root on a SSD & Swap & /home on a HDD, am not going to discount their ideas, yet some of these doesn't work in my type of install scenario. Everyone has a unique setup, their preferred way of doing things, what works on some installs, doesn't on others. Though the drag & drop method of the main Home folders to an external works on most any install.