Portrait-0030.png
Your eyes are your first critic. If they don't approve, something is off.
Front-facing portraits leave no room for even the slightest misplacement of a feature. The trickiest part is always that no subject looks at the camera straight on. Even a slight tilt or rotation throws off the proportions.
But the real trick is not to get too caught up in the realistic details of the subject. Adjust the tilt and rotation if you have to. It's far better than ending up with a visually ugly portrait.
Portrait-0030-ref.png
Portrait-0030-ref-with-loomis.png