Yeah, it takes some time to get the hang of. I started playing around with it maybe 3 years ago. But, once you do get a good feel for it, you will find it a very useful tool! I'm trying to push myself to use it in more places.
Just remember these few tips...
- Keep it thin. I started out using GW's pre-made glazes. I still thinned them down 1 part glaze to 1 or even 2 parts water. That's the difference between a table top glaze and a display/competition glaze. Thinner let's you build up the color more slowly and helps with the blending.
- The color will be faintest where you start your brush stroke and strongest where you end it. So start the brush in the transition area and push the paint where you want it to go. So, for the stubble effect, I'd start near the top of the stubble and bring the brush down and under the chin. This helps blend it at the top and lets the color be stronger in the shadow area. Same goes for the red on the nose, start at the front of the tip and drag the color down and under the nose. For the bags, I'd start in the center and push the color towards the inside corner. Etc.
- Don't overload the brush. Dip it in the glaze and then dab it on a paper towel. Too much paint and it will just run everywhere like a wash. By wiping off the excess you will have much more control over where the color goes. I'll often test the glaze on my hand to see if I've got the right amount of paint on the brush and if it's thin enough.
- Let the paint dry between layers. You want to build up the color of 3, 4 or more layers (depending on how thin the glaze is and how strong you want the end effect). But, if you apply layer 2 while layer 1 is still wet, you just end up pushing layer 1 around and making a mess. To build up color, each layer has to be dry before you do the next one. Doesn't take long, but glazes dry a bit slower than regular acrylic. So slow down a bit and, if you want, you can gently blow on the figure to speed up the drying.
- Finally, glazes are easier to see on top of light colors rather than dark ones. Doesn't mean you can't use them on other colors, but expect it to take more layers to show an effect. Skin is usually light, so it takes glazes very well.