In your latest post (#124), the veins kinda look like cracks in marble to me. If that's the look you're going for, then it's working. If you're actually going for veins, I'd say that the one in post #117 (on the right side of the image) is a little closer. Maybe it's because the skin has a little more texture and shading in those screen shots. Perhaps if there was less B&W contrast (lighten the veins up a little), they would look more like veins under the skin, rather than cracks in the skin's surface. You might also try some light and shadow on them (bevel and emboss in Photoshop). I really like the pattern of the veins: they're balanced (not too much white skin, not too much veiny areas).
In the image where you ask "Or is this better?" (#117 again), there is an interesting pattern on his forehead that I think would make a neat tatoo, like Ulic Qel-Droma or Exar Kun.
The eyes are a great color, they're emphasized by the gold head gear. Maybe the whites of the eyes could be a little blood shot too?
I hope my suggestions are helpful. Keep up the great work