I think you have done a repectable job and her likeness and mood have come thru. The main problem is her two eyes are not properly aligned. Too much dark hair/shadow under her right jaw also make her posture uncomfortable.
The proportions are very good! Hope to see more work in the future!
If you're going for the 'realistic' look here are some suggestions- (you may know them anyway).
Drawing is all about light and dark - If you want to create more depth use darker grade pencils (2B or 4B) especially to eccentuate eyes, lips, etc.
Make use of your eraser as drawing tool - for highlights (reflections of the skin, eyes, lips, etc).
It's good to see more skin tone on her face - do the same for chest and arms. (otherwise it looks like her face is sunburnt.)
I'm sure your friend will love it - interested to see finished work!