A sketch is a quickly executed freehand drawing that is usually not intended to be a finished work. The word sketch comes from the Greek word "schedios," which means "made suddenly or offhand." Any medium can be used for sketching, but dry media such as pencil and pastel are normally preferred, and pencil sketches are most common.
Pencil sketching is an ideal way to try out different compositions or design ideas, and it can sharpen your ability to focus on various parts of a subject. In many cases, well drawn sketches can be objects of art in and of themselves.
As with any art project, the best results are obtained when care is taken in the selection of materials, understanding the principles and techniques, and practice, practice, practice.
Materials: Unlike other art forms such as oil or watercolor painting, pencil sketching requires only a minimal amount of equipment. All you really need are some pencils, suitable paper, a pencil sharpener, and a good eraser. If your intent is a sketch that is a finished artwork, at least two different types of pencils varying in hardness and blackness are advisable; a 2H or HB (hard lead) for preliminary drawing and a 1B or 1H (soft lead) for finished work and shading. The letters H and B are used by the pencil companies to designate hardness (H) and blackness (B), with the lower numbers being softer and lighter, and higher numbers being harder and darker.
You will want a sharp point or a mechanical pencil to do fine lines and small details in your drawing, and a broader point for large areas of shading.
Any kind of paper can be used for pencil sketches, but a good quality paper with a slightly texture gives the best results. Many artists prefer white paper, but off-white, or slightly beige colored papers bring out the texture of drawings and add depth. Art supply stores sell pads of sketch paper and sketch books of varying sizes that are ideal for pencil sketching. If you want to keep your sketches neatly organized, sketchbooks of various sizes are best.
An X-acto knife makes the best pencil sharpener as this allows you to vary the shape of the lead for different effects, from very fine points for small details and fine lines, to broad surfaces for shading or pencil washes.
The best eraser for pencil sketching is an art gum eraser that can be purchased at any art supply store or hobby shop. The art gum eraser is better than the hard generic rubber erasers as it allows you to pick up grains of pencil dust off a drawing without smudging lines. It can also be used to lift highlights out of shaded areas and created textured effects in drawings.
You need a well-lit, sturdy drawing surface, but in a pinch, you can balance your sketchbook on your lap or knee.
Techniques: The first thing that must be mastered is holding the pencil. There is not one correct way, but the way that is comfortable for you. The key is to hold the pencil so you don't get cramping in your hand.
Begin your pencil sketch by visualizing the final picture, then using a hard lead pencil, lightly drawing in the basic shapes to indicate where elements will go (circles for heads, lines for roads and trees, etc.). As you begin to add details, you can move to a softer, darker lead to put in areas of shadow. It's best to work from light to dark in a drawing, as this makes it easier to correct mistakes. The darkest shadows should be put in last.
Once you're satisfied with your sketch, you can protect it from accidental erasure or smudging by spraying it with a pastel fixative that can also be purchased at your local art supply store.