Eyes are one of the most important features on a face. They catch your attention and they make you forget about any imperfections of a portrait. If the sketch of the eyes is perfect, then you can reveal all the secrets of the person that you are drawing. All the feelings and emotions can be shown just with the eyes. But if you fail drawing the eyes it can ruin the whole portrait. You can find out how to avoid it by reading My Tip #4.
The Secret is that the eyeballs are almost never white! I know it sounds crazy, but the truth is that realistic drawings and paintings don't have absolutely white colors. When you do the eyeballs white, it automatically makes them look fake. And this is the most common mistake among realist artists. But be careful with shading, as well, don't make them too dark. You should find the balance between the skin tone and the highlights. The brightest parts of the eyes should be covered with only one light charcoal layer. Then add some more shadows slowly. The darkest part of the eyeballs shouldn't be darker than the darkest tone of the skin.
Sometimes it is really hard to work with charcoal when you are drawing the eyes. But once you feel how it shades you can manage even the small details. More detailed tutorial on how to draw realistic eyes is coming soon.