This is Sgt. Sienos of the Imperial Fists. I painted him up partially to give myself practice of painting yellows, and also as one of my friends is starting Imperial Fists, to help him out. Unfortunately I couldn't get a hold of a camera to do WIP shots, but here he is finished. Please comment and let me know your thoughts!
The yellow was done over a white spray, with three thinned coats of Iyanden Darksun. This was washed with multiple coats of Gryphonne Sepia, before being highlighted with light drybrushing of Iyanden Darksun, and varying mixes of Iyanden Darksun and Dheneb Stone (roughly 3:1, 2:1, 1:1, 1:2 but it wasn't exact). This was washed again with the sepia wash, and some Devlan Mud sparingly in recesses. Again this was highlighted up a little with the same mixes.
The black power fist was based in 2:1 Adeptus Battlegrey: Chaos Black. Then, I used Adeptus Battlegrey to highlight, before giving a heavy Badab Black wash. Edges were highlighted with the Battlegrey again to define them more. This was also applied to the chest
part of his backpack and his belt.