A good perspective will greatly facilitate your process. It is very easy to find: turn your head in front of the camera, take a few pictures and find the one you like the most. This will be your successful perspective.
Do not forget that the camera should be directly opposite your face.
Do not take full-face pictures, leave it to photos on documents. Experiment with positions; it is better to turn your face 30–45 ° to the camera - in this way the picture looks more voluminous, and the line of the chin does not merge with the neck.
But in which direction to turn your face, depends on your features. The right and left sides of the face are slightly different: one can be more symmetrical, the eye is slightly bigger, in addition, there may be moles or some kind of skin roughness.
Choose the side with which you are best off: first take a picture of yourself with your right, and then with your left hand and compare the result. Which side is more photogenic, that should be closer to the camera.
You can take a selfie by lifting the camera above you - you will see not only your face, but also the surroundings and, if you're a girl, your neckline. In addition, when the camera is located above, the eyes visually enlarge, and the chin becomes narrower.