Made in Paint Tool SAI, arranged in PSE 8
Well, there was supposed to be a shading example of lighting with temperature, but it looked terrible so I dumped the idea.
I applied the shade with the lineart on top with the base colors on the bottom. Then I used the water tool to blend in.
As for shading, try shading on a darker background. You'll have a better view of shading. In a realistic perspective, the base colors are usually around the middle of the palette.
For a more natural look of the lines, i recommend the pen tool, and don't just use black
you can also use a dark gray, brown, etc.
I don't recommend using the Line work layer, where you can manipulate the line. It doesn't help your train your hand eye coordination and it doesn't usually do well with natural strokes since it slightly changes it when you draw.
I should be studying for the finals next month X)
If you need any questions, please let me know