Backing Up a WP Site

What is the most straight-forward way to backup my site. My site just got hacked and had to rebuild from scratch.
Is there a way to do it all in one shot other than copying my files and folders from the ftp to my local disc?
Are there specific folders that I should always back up? Or do I do the whole shebang?
When I make changes as time goes on are there any “wp operational files”
that will never change that don’t have to be backed up every time?