Use a fixed setup and simple reference marks. Mount the camera on a tripod or other stable support, and keep it in the exact same position each day. Mark the tripod feet on the floor with tape so you can return it to the same spot. Also mark where you stand so your distance and body position stay consistent.

To help with head placement, put a mirror behind the camera and draw a large oval or guideline on it. Then you can line your face up to that shape before taking each photo.

For expression, don’t aim for something complicated. Choose a very simple, repeatable look—such as a neutral face or a slight closed-mouth smile—and practice it a few times in a row to find what you can reproduce most reliably.

You probably won’t get every frame perfectly identical, but a stable camera position, fixed standing marks, and a visual guide will make the sequence much smoother and easier to align later if needed.