Oh my gosh I love this manga! ^-^ Vampire knight is WAY better than Twilight. This drawing is really good, you got Matsuri Hino's style in manga.
The hair is amazing, you do far better than I do with that! The roses; wow! Yuki's facial expression and features are excellent. Zero's expression is well drawn as well. You did a fabulous job! I'll give you an example of my work.
Its a rough sketch, and I need to clean it up but you get the point. :)