Take a copy of the SD card on your PC in this configuration. This is your backup.
You can then reflash this if you run into further problems, without having to go right back to a clean installation
I should also have said:
do this every time you get a stable working system - you can leave the copies of your earlier stable versions alone, or overwrite them if you're certain this is the new truly wonderful and definitive version
This means you can roll back to earlier versions whenever you want without tearing your hair out and getting worried about how to undo what you've broken. You go back to how it was before you broke it and have a chance to break it in a completely new, different and wonderful way
(I really should listen to my own advice and do this more often)