Most before and after photographs in aesthetics are useless as clinical records. They are taken in different light, at different angles, with different expressions, and frequently with the patient tilted slightly towards the camera in the after shot. As marketing they are questionable. As evidence they are worthless.
A record photograph has one job: to let you or someone else compare the same face at two points in time and draw a fair conclusion. Everything below serves that.
Fix the position. Same distance, same height, camera at the level of the area you are photographing. If you shoot the midface from slightly above, you will flatter it, and you will flatter it inconsistently. Marking the floor with tape where the patient stands is unglamorous and solves most of the problem.
Fix the light. Any consistent light source will do, but it has to be the same one every time. Overhead room lighting casts shadows into the nasolabial folds and under the eyes, which means those areas will look different depending on where the patient's head happens to be. A light source in front of the face, at face height, is more honest.
Fix the background. Plain, matte, and always the same. A cluttered background makes it obvious the two photographs were taken in different circumstances, and it will be the first thing anyone notices.
Fix the expression. Relaxed, mouth closed, eyes open, looking straight ahead. For anything involving muscles of facial expression you also want the animated views, taken consistently: frown, raise, smile. The static shot alone will not tell you what a toxin actually did.
Take the standard views every time, even when the treatment is only in one area. Front, both obliques, both profiles. It takes an extra thirty seconds and it means that when the patient later asks about something you did not treat, you have a baseline.
Remove the variables you can. Hair tied back, jewellery out, makeup off where practical. Makeup in particular will undo everything else you have done, because it changes the reflectivity of the skin.
On storage, treat these as health records, because that is what they are. They should be held securely, kept for as long as your professional obligations require, and not sitting in a camera roll that syncs to a family tablet. If you use a phone, use a dedicated app with its own protection rather than the general photo library.
Consent for the record and consent to publish are two different things and should be recorded separately. A patient agreeing to clinical photographs has not agreed to appear on your website, and treating those as the same thing is a reliable route to a complaint. If you want to use an image for marketing, ask specifically, ask afterwards rather than in the middle of the consent process, and make it easy to say no. Note also that promotional use of images can bring the material within advertising rules, which is a separate consideration from the clinical record.
Take the after photographs at the review appointment rather than straight away. An image shot while the area is still swollen misleads in both directions and tells you very little.