I did a cursory search for other painted examples (just to see what others have done), but it seems not many are that bothered with these models... they should be though.
Technique: there was absolutely no 'flat' painting on these, all was done with washes of two primary colours (over Vallejo white primer): Vallejo Prussian Blue; Windsor & Newton Finity Alizarin Crimson; Portrait Pinks from Liquitex, used for a little highlighting in between primary washes; some Vallejo Black for the eyes and deep shading; Daler-Rowney Silver ink for claws, etc. Base was sculpted with standard Milliput with bits of slate and painted in Vallejo browns, later darkened by mixing in some GW Charadon Granite.
I'm ambivalent about the basing: I was aiming for a streaking effect, to suggest speed, and the texture is OK-ish in that regard, but I found the lines were too linear during painting. Something more like a chevron enhanced by light brush flicking would have been better, I reckon. Anyways, they look decent enough as is, a touch alien, otherworldly (not a terrain you would easily find on Earth)...
Why silver ink. I had thoughts of alien physiology while painting these. I'm aware of things like comparative biology and such, but I didn't want to do the obvious 'bone' thing. Why couldn't an alien monster have evolved metal laced bone weaponry?
(yes, like Wolverine)