Tips To Add Dimension to Your Drawings

Flat-lining
Using a flat, solid line, especially around the outside of a shape, tends to flatten the shape.

Create line variation by adding thicker or darker line 'segments' to your lightly worked drawing.

Using this technique will help to suggest volume and creates more dimension and interest to your work.

Thin and broken lines will give an illusion of light striking your subject. Use this on the top edges of your subject (where light would normally be landing on it).

Thicker and darker lines will give the feeling of weight and shadow. Use this on the undersides and bottom edges to anchor your subject to the ground. You can also use this technique where one area overlaps another - this will give the illusion of a cast shadow and adds a 3-dimensional quality to your work.

Pear Exercise
Do a drawing of a simple subject, say a pear. Then erase small spots on some of the upper lines (where the light would hit it). Your goal is to make the line work look broken. Even one or two breaks will accomplish this.

Next, thicken up the bottom line work of the pear (where it sits upon a table or counter). This does not have to be one solid thick line. Try going from thin to thick to broken and then back to thick and finish with the line thinning.

Practice adding this to some areas of your work where you are sure it would go (where the light strikes the subject and where the subject sits upon a surface).

Observe other Artwork (especially animation, cartooning and caricature work - these styles often demonstrate this technique with great mastery).