Limit your Services
Keep it simple, reduce complexity.
What is your server going to do? Is it just a webserver, just an email server, a game server, or all three? If a system will not receive outside email, don't install a mail server. DUH.
For interactive UNIX environments limit local software to a small list and add to it when users request something.
Example:
345 packages installed on portal.adams.edu, 290 on staff.adams.edu, 845 on gozer.adams.edu.
IMHO, Debian/GNU Linux is the current king of the small initial install.