Create a Portrait with One Light

Actually in order to make a nice portrait you don't need many lights. If you have just one light source, it is enough, providing you use several reflectors to utilize and redirect the available light.

The main light may come from a softbox, at 45 degrees angle to your subject (from above). Then you need to place a quite large reflector below the model's face to bounce the light to the face.

Secondly, you need a fill light. You can set a simple white panel on the model's side that will reflect the light from the main source back to the model.

And finally if you place a small reflector above your model's head, you will have a hair light.

Such a setup can be also used when shooting on locations.