Answer to your question is not a forum thread, it's studying anatomy, light, art in all it's forms, design in all its forms etc.
It's about acquiring taste.
It's about training yourself.
It's about the hours you've put in.
I've never heard of a retoucher that is great at their job, that doesn't admire any sort of art.
You're essentially trying to "complete the picture" by DnB, and you need to have good reference points in order to achieve great results.