I had a few problems installing 12.04 and had to re-install 10.04 (needed a working computer that evening and didn't have the time to fiddle about trying to get it working properly). All I'd done in the way of backups was to copy the visible files in my home directory onto an external hard drive, which I'd planned to copy over to my new home directory - this is what I've done in previous updates.
It didn't take too long as I still had my 10.04 live CD and after downloading 200-odd updates and copying back my files things were back pretty much as they were before.
Before I try installing 12.04 again, I'd like to make a backup of my working system this time so that if things go wrong again I can restore things as they were, a little quicker.
I have a separate home partition. I understand that I can use something like Clonezilla to make a copy of my home directory (/home) to an external drive and then restore it later - do I also have to take a copy of the root file system (/)?
What else do I need to do? I presume that I'll somehow need to put the grub2 menu back as it was as well? If so, how do I do that, please?