I thought it was worth doing a quick write up of the paint scheme that I use for my Firewarriors and Pathfinders. My Tau army is based around a blue theme, with some orange trim. Of the "official" Tau schemes, it is most similar to Sau'cea sept. This is designed to be a very simple tabletop scheme with a nod to GW's Sau'cea minis in the Tau Codex.
If you are interested in a tutorial about a quick way of doing blue Tau-skin, there's one here. A similar tutorial for battlesuits is here.