Its easy to overlook something as simple as a can of black spray paint. Having has a few goes at trying to find a decent new car primer to use (since the original brand isn't sold any more) I've decided to return to model sprays.
A small can of Humbrol Matt Acrylic spray has helped me carry on priming in a normal fashion, and with good results. The previous sprays were either too shiny, or didn't provide Ideal coverage.
I also tried using a pink/purple tone for the skin. Having tried red skin and blue skin in the past, neither seemed to work, especially the blue, which was too close to the armour colour. GW's new chalky pinks (Daemonette Hide and Slaanesh Grey) work well, along with a purple wash. Its looking a bit dark at the moment, but I suspect it's all the unpainted primer still left, and the unfinished golds and bone.