Her eye Brows on the edges a little higher, Her mouth a little smaller. And one of the hardest to do is Capturing a persons eyes.  There is more problems with the eyes, than anything. Her Chin just below her lips start a triangle apearance.

These are only to be things to help you achieve what you are shooting for.

You need to get a picture of her face strait away, Place it as a background in front of your characture. Render your Taylor Swift then if you have an editing Program match them up one on top of the other. Fade on in an out so you can see the differences, same with the side view.

From there you can see the problems, and have all the answers in front of you.