awseome sketchbook, you drawing style reminds me very much of my own..
(wich is a good thing, i hope)
you should try rendering with an h pencil, it seems your using leads that are a little to soft for the tigh rendering your doing.
also, you should brush up on your neck anatomy. the human machine by george bridgeman has some good diagrams on the neck that might help. and as mentioned before the porportions on your figure are a little strange.
thanks for listening.
We act as though comfort and luxury were the chief requirements of life, when all that we need to make us happy is something to be enthusiastic about.