i see youre askin for crits so ill try to help

the shading is pretty ok and i see you have a pretty consistent light source but youve shaded w black it looks like
when shading know that shadows are not black but rather can be different colors

if you take a look at some things in real life youll notice that the shadows are not black but that they have color to them

take a look at this site: http://colormatters.com/
it has a ton of information on color

the other thing in this drawing is that the anatomy is a bit off and the lines are unsteady
the best advice i can give is two things: study from life as much as possible and practice your strokes

try doing some contour drawings/lines or simply practice your strokes by drawing some straight lines
heres a good guide on strokes to practice: http://www.learn2paintsigns.com/free_art_lesson_on_hand_lettering/basic-single-strokes-lrg.jpg