Basic steps to do after creating an Ubuntu VM.
Login as root:
ssh root@$USERNAME
Create new user:
adduser $USERNAME
Granting administrative privileges:
usermod -aG sudo $USERNAME
Set basic firewall:
ufw allow OpenSSH
ufw enable
ufw status
Enable external access to our user (assuming the root account uses SSH key authentication):
rsync --archive --chown=$USERNAME:$USERNAME ~/.ssh /home/$USERNAME