Airbrush all of the skin with a 50-50 mix of Ork Flesh and Vallejo Yellow Game ink.
Keeping the mix from the above step in your reservoir, add a little Kislev Flesh and further highlight exposed areas. I recommend sticking to the face, wings, elbows andbit where the light would hit.
Now add a drop of White Ink to the mix and add smaller highlights within the last stage.
I now coverred less area with a 1:2 mix of the above.
Now wash the skin with Darkoath Flesh , thinned with an equal amount of Contrast Medium .
Selectively edge highlight the skin detail in shaded areas with Elysian Green , with small highlights of Nurgling Green where relevant.
On the face and prominantn areas, selectively edge highlight with Ogryn Camo , adding smaller highlights of Pallid Wych Flesh on points and curves. I'd recommend paying particular attention to the face, since this is where eyes will be drawn.
Wing Skin Membrane
Basecoat the skin with Zandri Dust .
Build up a faux stretched skin texture with increasingly small lines (drawn into the centre) covering less area as you go. I transitioned through Zandri Dust , Flayed One Flesh and Pallid Wych Flesh , mixing as I went, to smooth the transition.
Now wash the skin with Reikland Fleshshade , pulling it towards the edges.