Faces

I decided to practice faces and expressions. I'm not very good at it. It generally takes me so much time to break down the form of the chin, eyes, nose, as well as their positions, and don't even make me start with the mouths. Lips are extremely difficult for me to do. I'll dedicate all my time practicing this part of the body solely. I'm hoping to gain a better understanding of all the aspects of the face, and that it helps me to reduce my drawing time. I spent at least 5 minutes doing the outlines of all the faces each, then 5 minutes or more doing the details. I'm very aware that doing the details is always going to take time, but investing more than five minutes doing the essentials aspects of the head is way too much (or at least that's how I see it). One thing I'm working on is stopped dividing the face using a vertical line from the forehead to the bottom of the chin, and instead drawing curved lines that define better the depths of aspects such as the lips, eyes, cheeks, etc, and I think this is helping me to make them more alike to the models.

Any tip or pointer is welcome!