just some tips *from a guy who only observes....*
-Eyes need to be "in a row".If you did it right, draw a line from the top line on the eye to the other eye, it will be straight.
-use the face guidelines to help you position the face and all
-don't try to imitate 100% of the LEAF style, that will really affect the outcome.
-and practice on the angles.
and here's some reference to help you draw