Start by sketching a "C" shape using an HB pencil.
Sketch another "C" shape within the first one.
Sketch in the inner ear, which resembles a "G," and add in the rest of the lines.
The finished sketch should look something like this.
Roughly shade over the entire drawing with an HB pencil, then blend in the shading using a blending stump or cloth.
Add in dark lines and shading.
Finish up the sketch by erasing the highlights and cleaning up the shading.