While I agree with Rich and Lisa on using only proper products as a professional I have to chime in.
When it comes to photographing glitter effects craft glitter comes in a larger cut glitter, which photos better than cosmetic grade glitter which is fine cut. Now both can come in a large or small cut but generally cosmetic is found in fine cut.
Cosmetic glitter is polyester, craft is both polyester and metal. Try to avoid the metal. It is the actual paint pigments used to color glitter that makes it FDA compliant or not.
Soooo, if the goal is to capture the glitter effect a larger cut glitter would be my choice.
I'd say keep it (non-cosmetic) off your models face. Be smart and safe. Yes hairspray in an option so is aloe vera gel, glycerin, body glues like spirit gum or pros aide. It all depends on what your model is going to do posein wise. How much movement she doing and hown much glitter you want to clean up. It goes everywhere!
When your ready for people products cosmetic glitter can be found at local drug stores to body art supplies (like www.extrememakeupfx.com