Aperture to control effect
The closer the subject is to the lens, the more dramatic the effect.
White/silver/gold will bounce light back into your subject, minimising shadows or highlighting the whites more. Reflectors work best when angled up to the sun - wiggle it around to get the light you want. You will be able to see the light bouncing. If it is cloudy, or there is no sun, this won't work, you will have to bounce light onto the reflector. Remember, you are going to reflect the colour of the reflector into your subject with the light.
Gold = warm tones
Silver = cool tones
White = neutral tones
Bring the reflector in closer.
Surround your subject with white so light bounces everywhere.