Here's my painting method, in a nutshell:
- Draw the outline of the subject with pencil.
- Paint the darkest areas of the image first. For example: the cast shadows*, hair and eyebrows.
- Paint the mid-tones and fully cover the canvas. I try to apply the right colors and temperatures based on my observation. Generally, the human skin would be warm (lots of red and yellow), the cast shadows would be cool (usually dark green), form shadows* would be a darker hue of the warm skin, stubbles on the chin and sideburns on males would be cool too (bluish or greenish grey). A tiny area right before the skin disappears in the form shadows would be a brilliant hue of red/yellow.
- I would wait a few days to let the paint dry. Then, I would make corrections as needed and finally apply the highlights (white mixed with a little yellow/red).
If I've been conscientious throughout the whole process, it would take me about four working days to complete a 16x20 painting!
*Cast shadow is caused by something blocking the light source. A form shadow is the side of an object that faces away from the light source.
