http://thedarkcity.wikia.com/wiki/Dark_Eldar_Tactica
Still under construction and contains a number of notes that are more 5th edition-centric, but the tactics section holds very true.
http://www.thedarkcity.net/t4935-dark-eldar-unit-guide-plastikente
Designed under 6th, I think the 'tactics' section is more of a basic bit of math hammer, but it's useful math hammer. Also, in my opinion, is too open with his takes on most units, but at least does offer interesting possibilities with all of them.
At the moment you're clearly in a very general mindset of what you want, so the broad stroke guides I think will serve you best for general ideas on how to build and what to field.