Before you start to draw remember that light travels in a straight line. Recall how to shade simple objects like spheres, cylinders and cubes. And don't worry about the materials you use. I use a 4B pencil only, regular drawing paper, a white eraser and a kneaded eraser.

1. Find the brightest light
Look for the brightest light that illuminates your subject. Outside the brightest light usually comes from the sun. Inside it could come from an overhead light, or a day-lit window.

2. Find where the brightest light bounces off your subject first
Generally, light bounces off a subject first where the subject is closest to the light. If you're drawing a table near a day-lit window, for example, light will bounce off the area of the table nearest the window first. In reality it will bounce off just one spot first. That spot splits the shortest distance between the light, the table and your eyes. This first bounce is where your subject will be the brightest.
As your subject stretches away from the light it will become gradually darker until the darkest spot where the light bounces off last. Both areas of light and of shadow become darker this way.

3. Shadows are darkest where objects meet
Where one object like a table leg meets another like the floor, the shadow will be darkest of all. And from this meeting point the shadow will gradually lighten toward the shadow's edge. Most all shadows lighten this way as they become more interrupted by reflected light. http://miketheuer.com/shading_example_sm.jpg

EXERCISE - Find a piece of fruit or any similar-sized object. Place your object on a piece of white poster paper. Fold half of the poster paper up in the back and support it from behind to create a standing backdrop. Then light your object two feet from the front and two feet to the right with a spot light or a lamp. Tilt the lamp shade toward the object. Whatever lighting you choose, be sure to shield your eyes from the light. Then draw!

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