This is coming out nice. Reminds me of comic book art.
What I've found to be important with things like this is bone structure. For example the jaw shape can make a huge difference. Just a few pixels sometimes.
The space between eyes, mouth and eyes, size of shoulders compared to head, etc.
In my opinion it's bone structure which is what makes a person attractive or unattractive. Also mouth shape. Just my opinion though.
And for females, soft, smooth lines are a must.
I found this was missing a mid-type color value, in my edit I used your green which seemed to kind of fit for that softer feel. I suppose one of the lip-pinks would have worked too. I took the highlights out of the hair just to reshape the hair.
I don't know how close you want to be to your reference, but I kind of shaded my edit with the head nodding forward a bit like the reference.