Not on this particular model, but in the past I’ve used a medium brown like Army Painter’s Leather or Monster browns. Then lightening it up some to do the highlights.
I’m not sure what the equivalent would be for other brands.
Thanks, I got Vallejo, Colours of War, Citadel, and Army painter. I got luck and I got Monster and Leather Brown, I will play with those for a bit and show results.
One thing I haven’t tried yet is to use a darker brown, like Army Painter Werewolf Fur, for the base and then dry brushing the previously mentioned colors over that for the highlight.
I’ve done similar with lighter skin tones to great effect, as you can get the effect of some highlighting, without actually highlighting.
Full disclosure: I have yet to attempt real highlighting, because of time and fear of needing to go back and fix it. So I use dry brushing to “cheat”.
Only reason I knew where it was is because I was looking at the Brotherhood of Steel model detailed on the next page just a little while ago and still had the book right beside when I saw the question pop up.