and your fast response will help you get vivid and absolutely natural images.
Photography is a great deceiver. In the shop window of a British photo studio one could read:
"Here you will get a photograph:
What you really look like - the price is 1 pound.
What you think you look like - the price is 2 pounds.
What you would like to look like - the price is 3 pounds."
No doubt, everyone wants to look good or, rather, immaculate. And here you may flatter you model if you learn several simple tricks.
Do not take a portrait photo at a short distance; it will distort the face greatly as if it were pulled out forward. But a friendly jest will be excellent, though.
If you mean to hide the double chin, you should photograph from the upper point, downwards, but do not show excess of zeal, otherwise while hiding one thing you may enlarge something else. If, for example, the model bows, the nose will look longer. I advise photographing a long-nosed model from the front because the side view will only emphasize this peculiarity. If a man is visibly growing bald, it's a good idea to photograph him from the lower point; in this case the bald patch won't be seen. You may ask me, "How is it advisable to take a photograph of a bald man with a double chin?" It is a very good question! During a photo session you will often have to face the challenge and your intuition and improvisation will be your best assistants. The combination of a bald patch and a double chin is not a rare thing. Here you can use several methods to hide the double chin. For example, with the help of clothes - a sweater with a high collar; with the help of the hands and arms - to prop oneself up on the chin; with the help of the lighting - to darken the lower part of the face.
A round face will look more refined if only part of the model's face is lit, the other part being in shadow. Yet, when taking a photograph of a human subject with certain blemishes (birthmarks, acne and spots, coarse skin) avoid lighting him/her from one side as it will uncover all the defects. The best solution to this problem is direct front lighting.
Photography is also an art of compromise with outward things. The ability to adapt all your equipment (i.e. your camera) to the performance of this or that task under various changing conditions is the best way to perfect photographs. You may, of course, rely on the camera doing everything on its own, but most often the result will be unsatisfactory. But to tell you the truth, sometimes significant works are produced accidentally. I don't think you are too ingenuous to hope only to good luck. Experience is your best teacher. Do not be afraid to make a mistake. The main thing is to realize why you have made it and to know how to avoid it next time.
Let all your photographs be excellent!