Wow. Significant facial construction problems. SwapBrain and EvilEye cover a lot, but I'll add to what they wrote.
Take a generic face and draw a line from eye to eye. Draw another one from cheekbone to cheekbone. These lines will be parallel when viewed from the front and slightly off parallel as the head tilts and turns. In your image the eyes are almost horizontal and the cheek to cheek line is at an absurd angle. Compare to the reference image.
You could fix this by raising the cheek, bu that may affect the position of the nose if you raise it too much. Consider lowering the eye (the one is shadow) significantly as well.
In a similar fashion, the line of the mouth will be along this same sort of angle, although this is subject to more variation due to facial expression, and tilt of the head. In this image, the mouth is pure horizontal, unlike the lines for the eyes and the cheeks, and it looks horribly wrong. The mouth completely ignores the tilt of the head and the line of the jaw.
If this were a cheap animation frame that would only be visible on the screen for a a fraction of a second you could probably get away with it. If this is for a static portrait image then redo the mouth completely, or else redo the cheek and jawline on the left side completely.
I took the liberty of removing most of the facial features. Where would you add the eye, nose, mouth?
The scars are too close in color to the hair, I also mistook them for hair strands on first viewing. Their dark outline separates them from the skin, so I think that could be reduced in contrast.
The lighting on the face is inconsistent. There is a highlight on the cheek, but no highlight on the surface of the nose that faces the same direction.
It's not all bad. The basic pixel work looks ok to me, although some of the AA is overdone (along the line of the nose, for instance). The hair looks good. The colors are good. I like the hint of an ear - it's a nice touch.
Hope this helps,
Tourist