Now while I realize that most people here are not looking for ways to make their painting take longer, I think there might be things here that some of you might find useful. So, the way I've been painting my orcs/orks lately, using a savage orc as a model:
1. Basecoat: 1:1 mix of Beastly Brown: Vallejo Model Colour 890, Reflective Green ( or GW Catchcan green, closest GW paint imo).
2. First highlight: Reflective green all over exept the deepest shades & recesses.
3. Second highlight: Ref. green - Camo green, ruffly 1:1 mix, leaving some of the previous layer visible.
4. Third highlight: Camo green, leaving again some of the previous layer visible .
5. Fourth highlight: Camo green - Sunrise yellow, about 1:1 mix again, , leaving some of the previous layer visible.
6. Fifth highlight: Previous mix + Bleached bone, about 1:1 mix again, , now concetrating on highest bitz only.
7. Last highlight: Pure Bleached bone, on highest parts only, like knuckles, brows etc.
8. Shading wash/glaze: Watered down Dark Angeles green all over the skin, more layers in the shades for deeper colour. Add water to paint untill it's translucent when you brush it on some paper. To avoid "coffee stains" and flooding don't use much paint - I wipe the brush along a tissue paper before I touch the model.
9. Last shading wash: Scab red + Gobling green 2:1 mix, lots of water again. Paint only the deepest shades and any other bitz that might need colour, like I did with the insides of earlobes, lower lip etc. After this I retouch the extreme highlights with B. Bone and paint over the spillages with black.
That's about two hours work on a single orc's skin ( who'll stand in the middle of the back row ). As most orks have less visible skin it takes less time, but still rather long...