i draw it by charcoal and charcoal pencils on the paper ,
it is very nice to shadowing with charcoal powder , and also i use papers and brushes , to do shadowing , sometimes i need to use my finger too . but it rarely happens, because the brushes are great for charcoal painting .
for the white parts just leave the paper to stay white , and for little white parts like dots and light of eyes , you can use eraser ,
hope you like it , cheers :)

i wanna show you steps of my work here :