You should already be a little familiar with CM before reading this, as her movespeed and squishiness make her tough to just pick up and play without any problems.
This build is matched to fit my style of play, which is very agressive--CM's Arcane Aura gives free mana regen, so there's no reason not to spam your spells early on.  Because of that, CM is at her strongest in the earlygame and tends to lane best with gankers who can snowball into semicarries or hard carries.  Keep that in mind when picking CM.