Thank you! I thought it would be fun to put up a tutorial. Keep in mind that there are many other workflows and this happens to be the one I personally use (though it’s constantly changing, like with any other artist). And to stay on topic, let’s use our dear majesty:
First we gotta part with a midtone canvas. Using white or black as a starter color is going to result in more difficulty to separate the light family from the shadow family in your palette, which brings us to the next step:
We gotta define planes by adding a clear shadow. Remember: shadow is everything about planes. A base shadow has to be relatively simple and defined, responding to the surface of the respective material. Don’t be afraid of using hard edged shadows, which are used when an object is casting it. Soften the shadows when they’re transitioning from midtone to dark.
Next, the light. Be sure to have a clear lightsource when you’re sketching! Lights are basically another world that answer to the material upon it. And remember that even in the light family, there are dark spots (which we’ll be seeing later on).
My personal favorite: ambient lights. Those are the lights present when there is no direct source present, like when you’re in the penumbra. This adds depht to the shadow family, and you might vary it’s brightness depending on the environment.
Subsurface scattering! This one is to be used sparingly, because it’s present mainly in translucent objects. It’s a line of separation between direct lights and shadows, so don’t overdo it with ambient lights. Although you can sometimes bend reality here and there, but you ought to observe it carefully first.
Next, ambient occlusion where ambient light doesn’t exist) and midtone lights. My palette is rather limited, but you can push your darks here as much as you like- as long as you remember the golden Proko rule: don’t let your lightest dark be lighter than your darkest light. Doesn’t roll of the tongue, but it basically means to keep the families separated.
And finally, highlights. Everyone loves them, and they’re used to make everything pop out, although they’re often overdone. The secret is to keep in mind the material you’re working with. His crown, for example, is metallic and prone to have a lot of highlights. Things like clothes or uneven surfaces, not so much.
This was pretty much a rough showcase and there are plenty of other factors to consider (like rim lights, terminator shadow), but the basic rules are there. I strongly recommend making studies of objects in real life, because they can often change your perception on how light works. As an artist, readability is a very important focus, regardless of how much stylization there is.