Use soft front light

Face a window or fixed lamp. Avoid mixed screen glow, harsh overhead light, and backlighting because they change how redness and texture appear.

Keep the lens straight

Hold the camera parallel to your face or tracked area. Match front, side, forehead, chin, or jawline angles across sessions.

Do not filter the image

Beauty filters, smoothing, makeup, and heavy compression can hide the very changes you want to track. Use plain photos for the clearest comparison.