Painting the Face
I like to start painting with the face. I begin by base coating the face with Rosy Shadow. I also base coat all of the sections adjacent to the face. So for the hat and collar I used Pure Black and for the hair I used Brown Liner, I use a bit of water to further thin the paint, so the base coat take about 2 to 3 layers for full coverage.
I then sketch on the shadows. I use two reddish browns mixed with the Rosy Shadow (about 3 to 1 brown to rosy shadow). First Chestnut Brown for the basic shadows and then Mahogany Brown for the darker shadows around the eyes, under the nose and chin, and in the mouth. From there I take care of a few of the facial details. For the eyes I start with a coat of dark pink (Violet Red + Rosy Skin). This is then covered up with an off white (Weathered Stone, and Weathered Stone + Leather White), but some of the pink remains at the corners of the eyes. I then paint in the iris followed by a dot of pure black for the pupil and then a dot of pure white for the catch light. With larger figures it's easier to put more detail into the eyes. Try to do as much as you can, but if it's too small feel free to simplify the approach. You can skip the iris and just use a black dot for both the iris and pupil.
This figure is baring his teeth, so I used some Bone Shadow and Aged Bone to paint them in. As with the eyes, avoid using pure white. These aren't getting direct light so they would not be that bright.
With the details finished I move to blending in the shadows. I start with the brown and Rosy Skin mixes and slowly add in more Rosy Shadow until I'm up to pure Rosy Shadow.
From there I start to add in Fair Skin to create the highlights. When I'm at pure Fair Skin I start to add in Fair Highlight for the top highlights. Use the highlights to further define the shape of the nose, tops of the cheeks, and chin.
I now switch to the remaining facial details. The hair starts with Brown Liner, then into Muddy Brown. To that I add Tanned Skin and at about 50/50 Muddy Brown and Tanned Skin, I start to instead mix in Fair Skin for the top highlights. Be a bit random in your highlight placement (within reason) to pick out certain parts so the hair doesn't look too uniform. I also take care of the lips, using Rosy Shadow mixed with Violet Red. To that I mix in Fair Skin to brighten it and create the highlights.
At this point the face looks pretty good, but it's still a bit flat. To create a more lifelike look I used several glazes. I take GW's Bloodletter Red glaze and Guilliman Blue (I also mix the two to form a purple glaze). In each case I add at least an equal amount of water to keep the effect subtle and allow me to slowly build up color. The red is applied in multiple layers to the cheeks, top of the nose, and bottom of the ears. The blue is used on the lower part of the face to create a subtle stubble effect. I used the purple to deepen the shadows under the eyes, in the deepest part of the cheeks, and under the chin. It's a simple enough technique but I think it really adds to the overall look. The nice thing is, no matter what approach you use for the rest of the face, the final glazing step should still work.
6 attached images. Click to enlarge.