Here's a link
to a comprehensive guide to backup and restore Evolution data. It's not difficult and straight forward. Just copying stuff as you preferred.
PS: If you want just to get a backup of the address book you can always export (save as vCard) and import (File --> Import) it later.
And you'd be happy to know there's a suggested plugin for backup/restore in Evo 2.12 series, and is in testing. Hopefully we'll see it soon.