The tau army I currently play is somewhat more infantry based. Not listing the upgrades, special wargear, etc., I use twelve fire warriors, twelve Kroot, six pathfinders, a crisis commander, a devilfish, and three stealth suits with a marker drone. This army has been working surprisingly well. But i'm also thinking about starting more of a mechanized list. Only time will tell. In the meantime, my color scheme involves the armour and most of the peice being shadow gray. The cloth and the like is codex gray. I then add detail with blood red, ultramarine Blue, Chaos Black, And fiery orange. My kroot are mostly fiery orange (I like the idea of using the accent color of the Tau for the kroot's main color) while the spines on the head are Ultramarines Blue.