I’m starting to backup before updating system.
For saving Safari Bookmarks, there is a switch that can be turned on to display a Debug menu:
% defaults write com.apple.Safari IncludeDebugMenu 1
The Save folder in my Documents is part of my backup routine so that is where I export a copy of the bookmarks:
Safari > Debug > Export Bookmarks… -> Documents/Save/
Address Book makes it easier with a command in its File menu:
Address Book > File > Backup Database -> Documents/Save/
