Here is a quick step by step on painting faces. I'll be writing a much more indepth tutorial on this figure, this is just a sneak peak.
That are a lot of different approaches to painting faces, this is one that has worked for me. The following example is a 54mm face (for Pegaso's French Dragoon) but I follow the same general idea when painting 28mm, 75mm, and 90mm faces. The main difference is the level of detail I can reasonably expect to achieve. Check the Roman work in progress to see a similar approach at the 90mm scale.
The following numbered steps correspond to each row in the image series seen below. Unless otherwise specified the paint names refer to Reaper Master Series paints.
1 - The face is base coated with Rosy Shadow2 - I rough in the shadows with mostly Chestnut Brown (I like to use a reddish brown for the shadows) but then a bit of Mahogany Brown in the darker shadows around the eyes, in the nostrils, under the chin, and a bit in the left cheek (his head is slightly tilted so the left side will be darker). The main reason I do this is to get the shadows around the eyes finished before I go in there to do those fine details.
3 - Start on the eyes
I first lay down a reddish pink layer (Rosy Skin + Violet Red) and cover up most of it with an off white (Weathered Stone). Ideally a little of the pink will remain in the corners.
4 - Eye details
I went in with a dark blue (Ritterlich Blue) and tried to get the shape of the irises. Because his head is slightly turned to his right I also painted the eyes looking a bit to the right. Straight ahead would have been fine, but to the left would have looked awkward. I then went in with a light blue (Ashen Blue) and tried to lighten up the irises near the bottom half, while retaining the dark border. Then, as carefully as I can, I add a black dot for the pupils and a dot of pure white for the catch light. Pretty tricky to do at the 54mm scale, so if you left the eyes at the dark blue stage you'd probably be fine. But if you can get those extra details that's great. On a larger scale, like 75mm or 90mm, I'd really try to get those in there.
5 - Returning to the skin, I go back with various mixes of Chestnut Brown and Rosy Shadow to smooth out the shadows I'd roughed in.
6 - Now I add in the highlights, with blends of Rosy Shadow into Fair Skin, and then into Fair Highlight.
7 - Details and Tweaks
Based on the previous picture I thought the highlights needed a little more pop, so I went from Fair Highlight to Linen White on the tops of the cheeks, tip of the nose, and a touch on the chin. I use a mix of skin tones and red for the lips, then repeat steps 5 and 6 for the ears. I also add in the eye brows with a dark brown.
8 - Glazing
This final step helps to add a little more life-like quality to the face. I take some of the GW glazes: Bloodletter Red, Guilliman Blue, and a mix of the two for purple (although further thinned down with water). I add some red to the cheeks (pushing away from the highlights into the shadows), tip of the nose, and ear lobes. The blue goes on the lower part of the face to change the tone for a subtle stubble look. And the purple is used to deepen the shadows in the cheeks, under the chin and jaw, and a bit around the eyes. Lastly I go in a touch up a few of the highlights as needed.