first, let me say that this is a very nice wip indeed, and it looks like it will turn out well.
the main problems i see with this piece is that it just doesn't look "evil" like the reference. he needs to more... i don't know... morbid.... i guess... try changing the palette on his face to a whitish tone fading into blue, and add more contrast. make his lips dark, i would suggest a palette of dark reds/ near blacks. also, if your not going to use a transparency, a black background would make the piece look darker overall.
i would make an edit, but sadly, i have no time.