I was told to look at some of these artist.

Eric Larson work.
Andreas Deja.
 Chris sander.
Dean Yeagle
Tom Bancroft.
Glen Keane.
Probably more but I'll start with this.


Side note: I found this interesting book called "Les Heroines Disney" Don't know how many pages but it has some nice sketches.

Also Disney need to make a real Art of The Little Mermaid. I can't find any sketches on Ariel human form. Maybe I'm just using the wrong words to search.