My initial sketches are always very, very rough. This piece is for an adult short story: Landlady by Roald Dahl.
Then I started with value study by using a big, textured brush. At this stage, I did't worry about colors, because I will add color later with a small trick.
I don't like working with too many layers, so only the backround(usually a grey color), initial sketch, and the painting layer.
At first I had the landlady standing behind the door, but then I changed the composition, because I wanted the viewer to focus on the young man's gesture, expression, and feeling.
Now let's talk about the trick. I added a new adjustment/curve layer at the top. Note: click "RGB", at the drop down menu, choose blue, red, or green one at a time, and adjust the curve to see how it affects the image. By using this function, you can give the image a new color.
Last but not the least, I added more details and the warm lighting effect, to give it more visual contrast.
It's not done yet. I have to refine it later.