Shows how to backup Mozilla stuff, either manually or with programs.
If all you want is bookmarks then use Library and export to either json file or html file. Then import/restore later.
I never bothered with total backup, only bookmarks and extensions. Get a list of them by using Extension List Dumper
If you have customized userchrome.css, usercontent.css and user.js they should be backed up too. Rest is just what comes, cookies, history, saving passwords etc. If you have done loads of about
:config "settings" then you should have put them in a user.js file - changing stuff in about
:config saves them in prefs.js, like registry for Firefox. Cant really back that up without keeping all the rest. User.js is your own changes and only that.