Shading and lighting

In this first drawing you can see how the cast light can effect the shadows created on a simple piece of cloth.
You can see the individual creases of the cloth and the implied position of the light source due to how dark and thick certain shadows are, which is also partially due to the thickness of the cloth. The darkness of the shadows are affected by any overlapping of the material as obviously more layers will create a darker shadow, which gives this drawing some depth.
When making this I tried to do both smooth shadows and strong lines as I feel it adds certain texture to the material as well as looking more interesting.

The second image was done by shading the cast shadow of a skeleton. You can see various effects such as dropoff and stretching due to the light source and its' angle to the skeleton. There are also darker parts to this drawing which are due to the distance of the light to various parts of the skeleton (i.e. the closer the light is to a certain part of the skeleton the darker the cast shadow is; and the way the skeleton has been posed.