To draw well depends on three things: observation, knowing how you want to translate what you see, and the physical ability to draw what you want. Here's a complete course in the art of drawing, from core sections on pencil and pastel to the more esoteric techniques of sfumato and gestural drawing. More than 50 drawing techniques are shown in clear, detailed, step-by-step photography, plus a comprehensive overview of digital drawing techniques, with directions for modifying digital drawings using a visual effects wheel. ENCYCLOPEDIA OF DRAWING TECHNIQUES also features an inspirational gallery of some of the world's finest drawings, demonstrating the full range of techniques in context.
The Encyclopedia Of Drawing Techniques: The Techniques