Very good basic drawing is there don't draw the teeth draw the gaps and a little lighter on the teeth edges. The distinction between the nose end and upper lips is ? perhaps less smile line on cheek and a small line for nostrill edge, Buy a putty rubber an learn to use as a light line drawer put small amout of shade on face and using rubber cut (erase) line for a light line. Easy to show you, difficult to write.

thank you for your advices i think i understand what you mean and i'll try to apply !!! thanks a lot, i need critics to make it better