Configuring new VPS.

Login to the server (via ssh).

$ ssh root@*.*.*.*

root@ubuntu:~# w

I want to create another user.

root@ubuntu:~# adduser youri

Make sure I can login as youri. 

 $ ssh youri@*.*.*.*

Escalate to root:

youri@ubuntu:~$ su root
Password: 

I want to disable root ssh login.

#PermitRootLogin no in /etc/ssh/sshd_config and service ssh restart

Logging as root says: Permission denied, please try again

Now I want to transfer my keys.

 $ ssh-copy-id  youri@*.*.*.*

spits out

/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: WARNING: All keys were skipped because they already exist on the remote system.

but after ssh-add ~/.ssh/id_rsa it worked and copied the key.

Ssh in again and passwordless login is working. 

Now I want to disable password logins altogether.

PasswordAuthentication no in /etc/ssh/sshd_config and service ssh restart

Add my user to sudoers:

root@ubuntu:/home/youri# usermod -a -G sudo youri

Set.