Don't use cardboard it can burn from the heat of the lights. Colors Gels can be used to change light colors on the set to create give the set interest or to bring out features or colors in people or objects. Don't's Rather than zoom in to set your shot, zoom out and move the camera closer to the subject. The shot will be steadier and of a higher resolution. Start the tape recording early as not to cut off the beginning of the talents scene.
Tape is cheap, use it.
Try recording a full 5 seconds before you even start the countdown to cue your talent. In the same vain, let the shot run long after the talent is done. You don't want the camera to back up over the end of your last shot. Many cameras act differently that way. Also, many magical moments were caught because the camera person had the patience to wait after the scene was over.