We are only a few days away from the Fedora 21 release.

 My Upgrade Checklist

1. Backup $HOME, /etc (settings) to external USB drive (Test random files with md5sum to make sure they are OK)
2. Inventory installed applications and settings and make a note of what needs reconfiguring after re-install (VPN, SSH Keys, GPG etc, custom compiled apps in /usr/local or /opt)
3. Download and burn Fedora 21 to USB or DVD from ISO Image http://docs.fedoraproject.org/en-US/Fedora/20/html/Installation_Guide/sn-making-media.html
4. Install Fedora 21 into a virtualbox vm to check the applications and settings you rely on are working
   1. I have just run into a PPTP VPN Bug which is a show stopper for me, so this step is well worth doing
5. Install Fedora 21 wiping old data (removes cruft)
6. Create new user account and login
7. Selectively copy $HOME backup to new user account (again leaving cruft behind)
8. Re-install favorite apps (GIMP, Thunderbird, Inkscape, Scribus, LibreOffice, QCAD, NetBeans etc)
9. Re-configure Web and Google Accounts, VPN's
10. Spend the next few days / weeks tweaking