The idea to this painting came when I sat down with my notebook in my sofa one evening, and tried to come up with something that was both upclose and personal, yet touched on larger issues, such as affairs of state. Preferably involving only two people, because I find that can often be more intense. A royal assassination, I thought, and since I like Fantasy, it became an idea of two fairy sisters, one of them Queen, and a serious case of sibling jealousy. I added a sleeping husband in the background, to supply one more possible reason for jealousy. Later, I came up with a whole screenplay based on this and two of my other paintings featuring fairies.
Roughly sketched on small notebook paper without erasing. No references at this stage, except for the curtain. I was happy with the first version, so I scanned it into Photoshop, cleaned it up, enlarged it. If you can, use a Wacom, I think you really need one for things like this.
Cylinders and Light
All good art courses teach the basics by making students draw spheres, blocks and cones in different lighting, over and over. This seems tedious and often useless to the beginner, but is the only way to learn about highlights and shadow. First you must be able to draw simple geometrical shapes (cylinders are good for the human body), with proper perspective and proportion etc. Then you must imagine the light and shadow. It helps to imagine the path of the light, then the bounce, and then its path to the eye - see it as balls on a pool table, bouncing off the sides. As you can see my sketch already included the basic direction of light - sometimes I'm unsure of which kind of light I want, but in this case it came to me at the same time as the initial idea. I wanted the killer's face dark, the victim's face and hand, and the killer's leg and back bright. I also wanted the light fairly directional and stark, but since it's night I also tried to keep as much shadows in there as possible.
Grey-wash on Sketch
Now I develop and clarify the lighting I had in mind, working black&white first because it's easier to only worry about one issue at a time. I use a hard-edged brush with pressure-sensitive opacity.
First, a mid-range grey wash over the whole image (New Layer, Multiply). Then fill in darker shadows. You should end up with 3 or 4 basic groupings of tone, from black to white. For the beginner, the simpler the better, so try to stick to 3: black or very dark, mid-grey, white or very light. You may not be able to stick to that formula, but it's good practice simply thinking about it.
Next I fill in whatever should be lightest. Note the similarities to the cylinder/cone sketch above.