Position the light source directly in front of you. Natural light from a window is preferable as it is usually a soft, even & natural colour. If it’s night time or the room is not conducive to using natural light, position the lamp behind and to one side of the camera. Try to avoid glaring lights behind you that will cause “lens flare’ in the camera.
Where available, use Indirect Lighting. Reflected Light gives a more even light across the whole face. Put some white paper, flat on the surface in front of you so that light reflects up to your face.