I think this is pretty god for a first attempt. I think just a little more practice with the Pen Tool and you'll be on your way.
The main issue I see is there is no delineation where the chin should be, it's just kind of all one color.
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Just a quick tip to help in the planning phase of any vector art project. I like to add a Cutout Filter to my subject and use that as a base to plan how I proceed. I prefer nice smooth flowing lines in my vector art so I'm not a huge fan of the Cutout Filter look, it's to jagged for me, but it offers some guidance as to specific areas I need to pay attention to.
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As for the hair, I would not have tried to reproduce as much of the details and would have gone for a larger blocked look with the added strands like John suggested.