(tested with 12.04 LTS)
ssh root@aaa.bbb.ccc.ddd
export DEBIAN_FRONTEND=noninteractive
apt-get -qq -y update && apt-get -qq -y dist-upgrade
adduser cowboy && adduser cowboy sudo
nano /etc/ssh/sshd_config
### change
Port ????
PermitRootLogin no
### add at end
UseDNS no
AllowUsers cowboy
### done
reload ssh
ssh-copy-id aaa.bbb.ccc.ddd && ssh aaa.bbb.ccc.ddd
sudo date
# if it works, root tab may be closed safely
bash -c "$(curl -fsSL https://bit.ly/cowboy-dotfiles)" && source ~/.bashrc