At RaMed studios this is the the lighting set up we use to bring out that flawless look
RaMed studios shares the process on how to set up,
Clamshell lighting needs two frontal light sources to illuminate the subject, helping to minimize shadows, blemishes, imperfections, etc. and really giving your client that glowing flawless effect.
Now when I say your 2 front light sources I don’t mean you have to actually have two lights. You can just use one speedlight and a reflector. For your main light, you want it relatively centered on the subject up at about a 45-degree angle in front of your client’s face. That way you can get some nice sharp shadows under the cheekbone and neck. (We know that every woman loves a little extra definition in those areas.) That light source creates a flawless complexion for your client. Eliminate hot spots on their foreheads or the nose by using a large softbox or diffusion panel in front of your light. Try different modifiers and switch up the height of your light source as well to see what that does for your client.
Your second light source or reflector is generally placed between the chest and belly button height on your client. Don’t have a reflector? Head to your local dollar store and pick up one of those foldable car shade window protectors. They work great. White Foamcore is also a great cheap option. Here are some really high-quality affordable collapsable reflectors. The object of that light source or reflector is to really fill in and soften those shadows. It evens out their complexion and creates a really beautiful catchlight in the eyes of your subject.