When you draw, you use lines to suggest light and dark values. The grade of pencil, the sharpness of its point, the angle of the point on the paper, the amount of pressure applied to the pencil, and the surface of the paper all influence the values you create. Even the pencil strokes you use influence the values you create on the paper.
Often type of stroke and the direction of the lines is determined by the subject. When drawing wood, the pencil lines will follow the direction of the grain; when drawing a cat, the direction of the pencil lines will follow the contours of its body.
Making the Grade
Here are some basic lines strokes created with different pencil grades. Hard pencils are good for sharp, crisp line work, and they keep their points longer than soft pencils. Soft-grade pencils can make smooth, dark values. Consider duplicating these pencil strokes as an exercise, then get creative and invent other textures.