I've just found 'Less is More'. and every time I try to highlight or blend more, the more it looks dark grey, or wierdly striped. Until recently when I really wanted to get some highlighting on my DElves, I'd taken to painting any area I wanted really black, flat black with no highlights whatsoever. cuz that's what black is. the ambient real light does enough to highlight true black. Semigloss can help too with the natural light. For the large black banners i've done recently, i'ts only to do a med/light drybrush of nearly black grey, and then the faintest of light drybrushes in light grey, and even then a little at a time so as to not repeat previous mistakes...