After reading this similar question I'm unclear how to require SSH keys for user, while denying SSH access to root (key or password). I'll use sudo after logging in as a user if I need to be root.
I know how to require SSH keys:
PermitRootLogin without-password
I know how to disable user 'root' from logging in:
PermitRootLogin no
I know how to whitelist a user:
AllowUsers user
I don't know how to put this all together (or if it's even necessary? - SSH key may be good enough). I would normally solve an answer like this through trial and error, but I'm afraid I'll lock myself out of this server...