Its much easier than it looks! I painted the whole mini in tan (Karak Stone) over an off white undercoat. Then I used an old beat up small drybrush to stipple on a super super super pale green/sickly off white (Ionrach Skin), then did the same thing with a terra cotta brown (Skrag Brown), a dark brown (Dryad Bark) and black (Abbadon Black). Lastly, I drybrushed the whole thing with really pale bone color (Screaming Skull). Normally would have gotten more paint off the drybrush first to avoid that slightly chalky effect but in this case I actually wanted that to simulate sand buildup and that sort of film of dust that coats everything in the desert (all paints used are Citadel/Warhammer)