(O_O) You're making a Death Note fanbook??? (from what I have understood ._.)
My advice is to add a darker tone inside L's mouth like what you did in Raito's mouth. @_@;;; And have a shadow under the top lip of Raito's and L's. CwC;;;;;;;;;;;
That's all!
EEE I'm sorry I didn't type the comment all in Japanese. This computer doesn't have Japanese language. (-_-;) It's frustrating me! Just out of curiousity, will you be able to read if I typed in Romaaji?