One of my favourite ways to use a light is a hair light. Add it to almost any picture to add some interest, contract, and separation from the background.
So you go from this picture of a very nice student in one of my classes recently:
…to this subsequent picture of the same young lady:
Much nicer, no? And look, even the smile improves!
OK, I am kidding about t he smile. But the picture is better. A dark-haired person against a dark background particularly needs a hair light.
It is aimed directly at the subject from the back, usually diagonally. Use a grid (like the Honl Speed Grid) or a snoot for even more controlled light (like the Honl Speed Snoot).