At first, it is very important that the actors have a comfortable position and enough stability. Ask them! They have to stay in this position for a few minutes! For the first pictures you should start with one sitting person and some satin material. Mostly it`s better to make a plan:
-which colour you want to use, decide where the brightest spot of the picture will be situated, which directions of light the picture should have...
IMPORTANT: You want to have clear eyes on your slide, without blur? - If the actor sits in complete darkness and he has no spot to look at,- his pupil will move while giving the light at the face. Decide in wich direction he should look, ask, on which spot he look at and there you have to mount a little piece of glowing or fluorescent material (1). So he can look at while exposure and you got no problems with the eyes. Take care: look through your camera - the flourescent piece shold not been seen.
Another piece you should mount at your camera (2) if you want to make a picture with a direkt look in the camera. It will help you too controling your own standing position while exposure. You should never stand in the direct line between camera and the spot you paint with light. After exposure the glowing spot at the camera will help you to find your camera and go back to unlock the shutter.