I recommend you to add some contrasted colors, you have green, so add red, emphasize highlights, add skin texture on separate layer, go to color channels and add some subtle changes there... There is a million stuff you can do since it's still a wip, and all of that should be directed toward making her face a bit lively, since, right now she is like a corpse...
Also, where are the ears? ;} If she doesn't have them, at least design some replacements.
I recommend you focus on her eyes and her lips, do the massive job there. Then on lighting and 'weed' around her face.
If you follow basic examples of digital portrait paintings you will notice that they always divide face to three zones, 'cold colors', 'hot colors' and mixture of those two. There is a reason for that.
You've also mirrored left side of the face to the right, like you are doing TB head texture. I hope you will add more changes to both sides so they don't look so 'perfect'.
If you need advice about shading and lighting, just ask. And start doing full figures. Don't be afraid of first steps toward full anatomy pieces...