Line

I been doing a lot of drawing lately paying attention to how line works. How different directions of line affect a drawing. For instance, a bunch of lines going in all different directions will create a atmosphere like effect. Lines running around the form will re-enforce that form. Think of an arm coming at you in perspective with the shading following the curve of the forearm. I've really picked up a lot of the book by Harold Speed called, "The Science of drawing." Highly recommended and can be had for very cheap on Amazon.com.