Create an administrative user
Create a regular user and grant only the privileges needed. Keep recovery access available and verify a second session before changing SSH settings.
Use SSH keys
Generate an SSH key on your computer, add the public key to your server and verify key access. Disable password login only after testing recovery and key access.
Configure a firewall
Allow the SSH port and the application ports you actually need. Test the firewall carefully so that you do not lock yourself out.
Patch and back up
Install security updates and set a backup schedule. Store a copy separately from your server and test the restore process.