spray this http://shop.warlordgames.co.uk/pure-...spray-30-p.asp
(don't need to spray white but I would anyway)
paint details (lining on pads, boltguns, eyes etc)
wash with devlan mud (experiment with thickness on spare models/sprue to get the right look)
your practically done, I find washes shade and highlight enough to not bother wasting your time.