Drawing Eyes and Faces

Facial expressions and eyes have been my recent fancy, specifically with how to convey an emotion. I started with the simplest faces I could, lines and dots, and tried to contort them into various expressions. I found that it is pretty easy to get an angry or sad fad, but much harder to get anything in between (kind of like that water temperature your shower can never get to). For the second picture, I added eyelids, eye lashes, the outlines of the eye in the socket, and eye brows. The brow on the left is a little cocked, with the attempted expression to be a "Really?". I have to admit I still don't understand how eye lids and eye brows interact with each other, but I do know that the gamut of expressions hides in that section of the face. Below are my sketches.