Been working on my faces lately, especially in regards to realism and proper construction.
In my mind there truly isn't anything harder to depict than the human face, it's astonishing how what essentially is nothing more than an oval shape can have billions of ways it can be depicted, and within each one of those there is yet another few hundred nuances of emotions that can be subtly added in various combination's.
These were drawn from a mix of photo references, artwork and largely my imagination. When I use photo/art references I consciously try not to copy it 100%, rather I focus on absorbing the forms depicted while also making my own interpretation of those forms and shapes to my own liking. Of course, this type of learning does initially lean itself to a lot of "hit and miss", especially since I also don't try and repeat my constructs, sometimes the results are good, sometimes they aren't.