This instructable will cover the basics of adding shadows and dimension to drawings as well as some basic rendering techniques.
The previous Instructables in this series covered the basics of selecting drawing tools, drawing posture, making a straight line, and drawing in 2-point perspective.
Here are my other drawing Instructables:
The easiest way to cast an accurate shadow from a simple figure is by dropping the top face of the figure to the ground plane and shifting it back as long as you'd like your shadow. (the higher the light source is the shorter the shadow is. Just like how your shadow is smallest at noon when the sun is directly above you and gets longer as the sun sets.)
Start with a simple shape like a cube or cylinder.
Redraw the top surface on the ground plane shifted back and to the side about half way.
Connect the front corner of the shadow to the leading bottom corner of the figure.
This area is your shadow.
If you're having a hard time visualizing this in perspective try first drawing it from a top down or side view.
Practice this technique from different angles with cubes and cylinders.
Remember that shadows still follow the rules of perspective and recede to vanishing points.
How does the shape of the shadow change when you move the light source?