I will introduce the process of this pencil drawing.

process

completing

At the beginning of the drawing, I have to be aware of the following always.

"Attention to detail too early, make light of the essential structure"
(From Nakahara method of "painting theory" )

Among the first to draw as if create a three-dimensional clay.

So as to draw come to mind by the image of the simplified structure the "plane",
I will continue to draw while capturing roughly the basic structure.

The "plane" will continue to decrease gradually from a big one.

Although I think you feel this way as a detour somehow,
It is a theory which is indispensable in order to capture the feeling of volume (stereoscopic effect) surely.