The portrait looks a little distorted. The left side (our left, the side with the ear) looks compressed in the vertical direction while the right looks stretched.
Some of this is the shading. Compare the long curve of the cheek on the right with the much shorter area of the light skin tone on the left.
Mostly I think it's that the ear has thrown off the basic alignment. The left eye, cheek, and ear are part of one view, everything else is part of another view. My suggestion is to erase the ear, redraw and reposition it based on the overall head shape (it may be useful to cover up most of the other features), then redo the left eye and cheek.
Hmm. Maybe the top line on the far side (right side) of the upper lip should be more steep? Lower the smile line one pixel on the right side? Not, sure, something is a bit off there. A reference pic would help.
The tree girl is a cool idea. There is plenty of work to go with the shapes and colors, but it's a good start. You could even animate it, having a tree sprout the human parts like she is stepping out of stealth mode. Also, the blue pixels in her eyes are invisible unless you zoom in, so maybe expand or remove them.
Hope this helps,
Tourist
