My Google fu these days is crap. But the concept is this:
- Get an external HD, format it to ext4.
- Copy your /home to it.
- Make a backup of anything else you find valuable.
- Use the distro installer to erase your / filesystem and create another in its place with Btrfs and at least two volumes: one @home and one @.
Instead of relying on the installer for that (many nowadays are simplified and don't offer much options), I like to use a live GParted ISO. The live GParted is a disk recovery/maintenance mini distro that has friendly graphical tools. You put it on a thumb drive keep it around just in case. And it can be used to create new filesystems like above.
Oh, BTW, keep your LVM+LUKS encryption setup. Not a time to be messing with that.
