1. Get an external HDD or SSD drive and put your home partition on it;
2. Get a fast USB pen drive (or another external disk drive, if you want) and put some random distro on it;
3. Boot from your the USB drive;
4. Login as the default distro user and create your user;
5. Mount the external home partition on your /home/user directory;
6. Apply a bit of chown and chmod magic if necessary;
7. Login as your user and try the distro;
8. Wipe the USB pen and burn another random distro;
9. GOTO 3.

Hey, it's great to try out some distros until you find the one that suits you. If your /home is on a different partition, you're mostly fine already (make sure you don't accidentally delete it!). Depending on your setup, you may have changed some files in /etc as well that you may want to backup. Also check your /opt folder and backup whatever you may need from there. When I reinstall, I also make a list of installed packages to reinstall afterwards so I don't need to look them up again.

Also, if possible, make sure you have a functioning second computer or at least smartphone with internet access at hand in case anything goes wrong :)

Otherwise good luck and happy distro hopping!