These notes on administering servers specifically applying to Ubuntu but can be adopted to any other *nix platform.
All practices outlined here are used on real production systems pruned and grown from hard earned blood, sweat and tears.
The articles are organized by tasks and ordered chronologically by how most systems would develop. Furthermore, they use a tutorial format that will result in a real working system.
Note, you do not have to read everything! The articles are written to allow for multiple paths. Each path will result in a completed working system to meet a specific goal.