Welcome to GDF. Do you really want crit on this piece? I'm guessing that's just for fun or a commission rather than a commercial piece?
It's a really cool drawing, but there's something a bit scary about the proportions of her face. Reminds me of an imp or a goblin. The colours don't help either. Her lips are really saturated and her teeth look odd sticking out from her mouth. She looks very slightly crosseyed to me too. Her left iris could be nudged to the right a bit to solve that. Her eyes with those 2 white dots in them look like buttons.
I love the lines in her hair though. Is each line an object with a fill rather than a stroke?
It is more fun to talk with someone who doesn't use long, difficult words but rather short, easy words like "What about lunch?"– Winnie the Pooh
sadly, the proportions are as is on her face. a link to the reference here, you'll see more of why it looks so silly haha. i never noticed the button-esque eyes, i just always thought of it as reflection and the crosseyed look is probably because she's looking at a camera close up haha. and finally as for her teeth, in the reference you'll notice her mouth is slightly open, but due to the size of the stroke around the teeth it wasn't really easy to make an opening
as for linework. all my work is done in photoshop, i just don't like illustrator at all other than for logos. using a simple generic tablet and pscs4 does the trick