Basic

• configure locales cheat locales
• slice system cheat slice-debian
• configure public key auth for ssh cheat ssh-pubkey
• change mirror in source list to a fast mirror
• security update apt-get update && apt-get upgrade
• configure hostname cheat hostname

Optional

• add a new user adduser foo (and setup public key auth)
• setup postfix cheat postfix
• hardening cheat harden-debian-server