Why the camera changes the picture.
A few small changes make your photos a more useful starting point.
Distance changes perspective.
A close selfie can make the nearest features appear larger relative to the rest of your face. Moving the camera farther away changes that perspective. Start around 1.5–2 metres away, with enough resolution to crop the image if needed.
Keep the setup simple.
Use soft window light or even indoor lighting. Keep the camera near eye level and use a neutral expression. Turn off beauty modes and avoid filters. A tripod or a friend can make the setup much easier.
Compare like with like.
If you are documenting a haircut or a new style, repeat the same camera distance, light and expression. A dramatic lighting change can make a comparison misleading. Think of the photo as context, not a precise measurement.
General styling and photography information. Individual needs vary; professional fit and clinical questions require an appropriate qualified adviser.