Also, try several watered down ink washes on yellow, as opposed to just one. Flesh wash is such a good universal ink, I don't even know why they make Chesnut. I'm also a big fan of brown for a more subtle look. Just beware Pooled ink on light colors is very hard to smooth out by painting over.
I've yet to try ink directly over white, my fear is, ink tends to have a bit of a shiny sheen to it, ran into that problem when inking faces and hands...probably easily solved with DullCote or matte sealant.
I tried the Iyanden Dark Sun paint too, and yeah, due to the high saturation of pigment they are a bit tricky. Solution: a little Liquitex Flow Aid and patience.
I still wouldn't recommend the foundation paints for vehicles. I dabbed on some of that on a Wave Serpent and almost cried at how chunky it looked. Almost.
I second P3 paints, really quality. I'm going to try Hearthfire over a white undercoat on my Eldar whenever I get around to it.