Without seeing the original its hard to comment on how well you've done so I'll stick to giving me thoughts on the finished image as a 'product'.
Overall its a good clean image, no obvious signs of retouching but it lacks a bit of 'punch'. It has the look of a clean, profession studio portrait but the composition and subject demand so much more.
I've attached a REALLY quick (2 mins) rough of a punchier version.
Her pores are also very harsh - particularly on the makeup parts - it makes her skin look rough and is not attractive. I know there is a bit of an obsession with pores lately - it seems to be the new fad but something that seems to be oft forgot is that pronouced skin texture is a sign of age and large pores are associated with greasy teenage skin. A number of cosmetics companies sell 'pore tightening' creams as a beauty product.
Children have tight smooth skin, as we get older our skin gets looser and 'battle worn', when we enter puberty our pores open up and exude grease (mmm sexy) and its downhill from there.
Only on a tight beauty shot should you be able to pick out individual pores. On and head and shoulders there should be indication of skin texture and anything further back they should be almost invisible. Smooth skin is GOOD, its perfectly airbrushed/blurred that should be avoided.
The lips also need work, you can see they are dry and she has a bit of a 'barrier' between the wet and dry parts of her lips, you should try to make them look a little more plump and succulent - kissable.
Edit: I see Craig posted pretty much what I said - was doing other things so this post took about 30 mins to write