Here’s a quick photo tip for you that will instantly improve your portrait photography: When taking a portrait, try to get catchlights in the subject’s eyes. A catch light is a highlight seen in the eyes from the light source you are using. They add sparkle and dimension to the eyes.
Catchlights vary in size and placement in the eyes depending on, well, the size and placement of the light source. Even if the main light source is behind your subject, you can still get a catchlight in the eyes by using a reflector. There’s no right or wrong size and placement to a catchlight, it’s simply a matter of personal preference (You know, art is subjective, man. Can ya dig?)
Above: where the catchlight is in the eye depends on where the light is coming from in the photo.