Focus on the "under-plane" (the nostrils and septum) rather than the bridge.
In the real world, there are no outlines—only where one shadow meets a lighter area. Secrets to Drawing Realistic Faces
Drawing a realistic face is less about "talent" and more about training your eyes to see shapes rather than symbols. Most beginners fail because they draw what they think an eye looks like, rather than what is actually there. Master the Proportions Focus on the "under-plane" (the nostrils and septum)
Use a kneaded eraser to "pull" light back out of dark areas for a glow. Secrets to Drawing Realistic Faces
The top lip is usually darker because it tilts away from overhead light.