I'm going to attempt to give a quick introduction to figure painting (with acrylics) and then talk about how I paint faces. To create my transitions and blends with acrylics I use layering. This is the application of many thin (semi-transparent) layers of paint to create the effect of a smooth blend. Another approach is called wet blending where you mix the acrylic with a drying retarder and can then blend directly on the figure through mixing the paint (much like oils, though still with a much quicker drying time). If you're comfortable with oils then it is worth looking for tutorials on wet blending with acrylics. However I will be focusing on layering as that is the technique I use. I should also add that this is focused on small scale figure 1/35 (54mm). I use the same approach of 28mm, 75mm, and 90mm. But, as you get to larger figures other approaches such as oil paints or airbrushing become preferable to brushed on acrylics.
An invaluable tool is my wet palette. You can buy one or make your own. I use a shallow piece of tupperware, a wet palette sponge to hold the water (other people will just soak a paper towel), and wet palette paper (other people use baking/parchment paper). I get the special sponges and paper at Michaels, an arts and crafts store. But you can make do with stuff from around the house if you wish. The wet palette has a reservoir of water that slowly diffuses through the paper into the paint, keeping it from drying out while you work. If you're mixing colors it will allow you to work with the paint for much much longer than you normally would before it drys out.
As for paints I really like Reaper Master Series acrylics. Unfortunately not many places carry them so most likely you'd have to order them online. They are similar to Vallejo Model Color acrylics and those are much easier to find at your local hobby store. Vallejo has another range of paints, Vallejo Model Air, which might be a better choice. For layer you don't want the paint to be too thick. You can add water to thin them, but the Model Air come a bit thinner so they don't clog the airbrush, making them a bit easier to use right out of the bottle. I will be giving the names of the Reaper paints I use, but you can check out the colors here: http://www.reapermini.com/Paints/corecolors and find similar shades in whatever brand you prefer to use.
When placing shadows and highlights I imagine a light source directly above the figure. The angle of the surface will dictate how bright it should be. A horizontal upward facing surface gets the most light and is the brightest. A horizontal downward facing surface gets the least. A vertical surface would get an intermediate amount of light and should be halfway between the darkest and the lightest tones. And so on for all of the angles in between. This is often referred to as Zenithal Lighting. If you want more information search for tutorials using those keywords.
To create my blends I usually begin with a thin coat of a midtone. In the face examples I'm using Reaper's Rosy Shadow. When I'm applying a thin coat the white primer will still show through. It takes two to three coats of the midtone to get complete coverage. Many people will work down from the midtone to the shadows, gradually layering on darker and darker shades, reducing the area applied each time. As a matter of personal preference I like the sketch in the shadows and then work up from dark to light. It just makes more sense to me. So for the faces I'll take a reddish brown, in this case Reaper's Chestnut Brown with a touch of Rosy Shadow, thin it a bit, and then sketch in the shadows (2nd image in the series). For the darker spots I substitute in Mahogany Brown and repeat the process. This goes around the eyes, under the chin, and in the deeper shadows of the cheeks. At this point I stop and paint in the eyes. For the whites of the eyes you don't want to use a pure white. It's too bright and the result will look more cartoony. Instead pick an off white like Reaper's Weathered Stone. I'll then add in the irises, pupils and catch light as best I can. It's easier at bigger scales of course.
With the eyes finished I turn to blending in my shadows. I start with Chestnut Brown and slowly start to add in more and more Rosy Shadow. Each layer is only slightly different from the layer before. Keep the paint thin so the multiple layers don't start to cake on the figure. They should also be thin enough so that they don't completely cover up the layer beneath. Through multiple applications you get your blends. The more layers you use (and consequently the smaller the difference between the layers) the smoother the end result will be. Work away from the deepest shadows and towards the midtone and highlight areas. When I'm at pure Rosy Shadow I start to mix in Fair Skin and work on the highlights. As the paint gets lighter keep reducing the area that you apply it. When you get to the top highlights (pure Fair Skin, then Fair Highlight) you're only applying them in very small spots like the tops of the cheeks, on the nose, and top of the forehead (assuming no hat or helmet). A highlight along the top of the lower eyelid will help bring out that detail too.
The last step in painting faces is applying glazes. This is were the face really starts to take on some life. Glazes are very thinned down paint. To create your own I recommend getting some Vallejo Glaze Medium. I've got a couple of the Games Workshop pre-made glazes so I use those (adding 1 or 2 parts water to 1 part GW glaze as they're still a bit too thick). To make your own take 1 part paint and then 2 parts glaze medium and 3-6 parts water. I'll test it out on my skin. You should see a tint, but it should be very subtle. The idea is to build up color over several layers so the transitions are invisible. When applying glazes and working with any thinned paint the direction of your brush stroke matters. The color will be strongest where you end the strong. So start in the transition area and push the paint where you want the color to be. A glaze differs from a wash in that you want more control over where it's applied. So after you dip your brush in the paint, touch it to a paper towel to draw off the excess paint. If you touch it to the figure and it flows everywhere, you've got too much paint on the brush. Wipe the brush on a paper towel first so the paint will go only where you want it to go.
For the face I'm working with three different glazes: red, blue, and purple. I use the red to add some color to the cheeks, tip of the nose, bottom of the ears, and perhaps some of the creases in the forehead. The blue glaze us used on the lower jaw and around the mouth to create the 5 o'clock shadow. Remember, it's thin so it doesn't look blue. It just changes the color enough to look like stubble. In each case I'm building up the color over 2 or 3 layers. More if I want it to be stronger. The purple glaze is used to deepen some of the shadows in the cheeks and around the eyes. Glaze medium acts as a slight drying retarder, so you need to wait 30 seconds to a minute or however long until the layer is dry before you apply the next one. Otherwise you're just pushing around the first layer again and you don't build up the color. In both of the attached image series the second to last image is before the application of glazes and the final image shows what that subtle color variation does for the figure. If you skip all the other steps in this tutorial, I recommend you at least experiment with some glazing. Even on a figure without any shading a bit of glazing can help make it stand out from the rest.
The two figures in the attached image series are a 1/35 scale Saxon from Latorre and a 1/35 fantasy barbarian figure from Olivier Bouchet (an independent sculptor). I'm putting together a full tutorial on that figure over at my painting blog, so take a look at that if you would like more information.
http://powellminipainting.blogspot.com/p/painting-gokan-slaine.html
This was a quick look at a topic I've spent years learning and practicing, so don't get discouraged if it doesn't turn out perfect right away. But, if you want to paint display or competition level figures, work on blending smooth transitions, placement of shadows and highlights, and using color variation to create a lifelike look.
3 attached images. Click to enlarge.
