I'm a beginner to pixel art and I spent the last hour working on this. I reached the point where the face is holding me back and I can't find the right way. So basically I need help making the face look right, any tips or examples will be appreciated

Also I'm looking forward to any C&C on the rest of the head except for the ears which look really bad.

Reference: http://i2.iofferphoto.com/img/item/803/905/26/hdZVuA8ZUljXls5.jpg

WIP: