Hmh. Try adding some of the nice handy tools, fade some things a bit.

Look for a light source. Maybe make a note, like draw an arrow somewhere on the top corner of the page to indicate where the light is coming from. So far you did pretty good shading the top part of her hair and the cleavage part *ahem*. It looks to me like it's coming from the above her. Put some darker tones on the inside part of her hair. Add some highlights to her cheeks or something using the small airbrush or one of the watermark tools, add some to the upper lip too, and right under the eyes too. Hope that helps. I'll help you shade it if you want.

[edit]Here's some tips created, thanks to Zack: Lineart Tutorial (which also includes how-to-shade)[/edit] You can go through those steps if you want, and then eventually, you'll get to step 3. :)

awwww thats really purdy