For bone I use Flayed One Flesh for the base coat, then a wash of Seraphim Sepia, then back to Flayed one Flesh, wet-blending with Pallid Wych Flesh up to the highlights.
As for metals, I can't help on the NMM as I've never tried it. I'm happy using the GW metallic paints. I give my Ironjawz the rust treatment - base of Leadbelcher with an Agrax wash, then stipple some Typhus corrosion on top, dabs of Ryza Rust (not too much), then pick out the edges with Ironbreaker silver.
Hope that helps.