Recently I started a forum thread where I offered to critique other people's art. This proved to be wildly popular. However, I noticed that some things which could be improved on are far more common than others. This is an attempt to explain the most common mistakes, and how to prevent those.
Lack of shading
This is something I see very often, especially from young artists. A lack of shading will make the drawing look flat and uninteresting. The highlights and shadows will make the drawing pop out more, and create depth to the drawing.
There are different ways to shade. Cell shading is a common method in digital art, while it's used much with traditional media. The traditional way of blending out the shadows and highlights creates more realism to the artwork, while cell shading is good for semi-realism.
In the example I've added
I - no shading at all
II - cell shading
III - full, "normal" shading
Not going dark enou