Shading is an important skill for every artist to develop. Every artist realizes or should realize the importance shading makes in his/her drawings. Without good shading techniques, drawing people and faces masterfully, is a moot point. Shading is a technique that every artist should attempt to master and practice continually. Shading requires certain tools and steps to be developed in order to master.
The ability to shade is determined on how well you can see value relationships, along with a basic understanding of how light works. Value, or how light or dark something is, is relative.
Like many things artists experience, no single value can exist by itself. Our eye will automatically lighten or darken. A medium grey will look almost white next to black and very dark next to white. When determining value, it is important to squint or open your eyes very wide. This keeps you from focusing in on a single value and look at all of the value relationships together as a whole. Without doing this our eye will play a trick on us. For example, if we focus in on a shadow area of our subject, our eye will adjust to that specific value field and give us a false reading. We will have a tendency to start averaging our values, making our lights to dark and our darks to light, failing to see the over all relationships.
Your sensitive touch to the pencil is very important in shading. Shading can range from blacks, dark grays, middle grays, lights, all the way to whites. Each of these tones is usually represented in your drawings. Your pencil and the pressure applied to it, is another key to shading. It is important that as an artist you understand pressure and pay attention to how it affects your drawings.
Blending is also a skill in shading. Blending graphite can be done easily with the correct method. Laying pencil on smoothly with the strokes close together (so much so that it?s hard to tell one stroke from another) is essential and necessary to good shading. A controlled stroke laid carefully with even pressure is important. I also recommend using the end of a kneaded eraser to help you blend.
Again, practice is the most important advice I can give any artist. Passion and practice will overcome any lack of talent.