One Head set-ups
With your light source angled roughly 45ยบ to your subject there will be dark shadows on one side of their face. The reflector will throw some of the light back onto the subject thus providing balanced illumination. You could increase the effect by using a silver (foil) coated reflector instead of a white one. Alternatively, if the portrait is torso only you could light the subject from above with a large softbox on a boom stand and reflect light back upwards using multiple reflectors (it may be possible for your subject to hold these reflectors, alternatively Lastolite make a 3 head reflector).
Your strobe should be set on a reasonable power to ensure there is enough light to reflect back onto the subject. If you were to use a larger softbox this power would need to be increased.
Two Head set-ups
For a two head set-up, another flash head can be placed in the same position as the reflector that was used previously. It gives a similar result but with more evenly distributed and diffused light. We still want to keep some definition in the models face, so a main light and a fill light is used. If light one is our main source then light two should be set on approximately two f stops less.
We want the models necklace and eyes to be slightly lightened, so a white reflector is directly placed underneath her and angled it upwards slightly. The softbox should be placed as close to the subject as possible (without being in the way of the camera) as this will increase the wrap around effect and negate the need for additional reflectors.
Three Head Set-ups
A three head lighting can be used as a fill light, catch light, spot light or a backlight. The two other strobes are kept in the same position and the third strobe is aimed against the background directly behind the model. A softbox isn't need on this flash head but an aluminium reflector can be used if you want a more intense lighting effect.
