Shading, how do you do it?

Question

How do you shade so the area is the same color, but slightly darker?

Like in the side of the face of the boy in this picture.

http://blog.bittorrent.com/editorial/wp-content/uploads/2007/09/ben10.jpg

How do you shade like that by hand?

Answer 1

hold the pencil at an angle and press harder or lighter

practice makes perfect

Answer 2

...and use very soft pencil for shading so that u can control the shading