Quite possibly one of the most overlooked aspects of lighting a subject is the rim light. Not only is it a great method to make your subject pop off the background, it's a quick way to give your portraits a very professional look. This helpful video will show you everything you need to know about creating proper rim lights.
Rim lights are exactly what they sound like: they illuminate the border of your subject. This is important particularly when your subject is wearing something similar in tone or luminosity to the background, which leaves them in danger of blending into it. A rim light is exactly what you need in such a situation. Even if that's not the case, it can add a nice polish to your portraits and give them a more three-dimensional and nuanced look. In this tutorial, Andrew Boey of Beyond Photography will show you exactly how to use them. Notice how he turns off his key light to check that the rim lights are set up properly; this makes it much easier than trying to figure out where your main light ends and the rim light begins. Try it at your next shoot!