The pose is very unnatural. Usually it is a good idea to turn the body slightly for a portrait to keep that pose relaxed. The pupils of the eyes are not usually that small compared to the rest of the eyes and give her a zombie look.
There are general proportions for the head that are off like the width of the skull and the distance between the eyes.
For skin tones, the nose and cheeks tend to be redder, the forehead slightly greener and the neck a little yellower. When I say slightly, I mean very slight shifts in hue.
Her clavical is too small and sems a little out of place.
As her form turns back into space they edges could be softer because they pick up more of the background color.
The light source seems made up. The light can't be brightest on the tip of her nose and be casting a shadow from her eyelids on her eyes. Same for the philtrum it can't be that dark if the light is shining on it
In general you have focused too much on surface qualities and not enough on form and angle of light in the scene