I have been asked to create a bust, I am ok with the body, but how do I make a 3D face? I am pretty sure I would use Rice Krispie treats...but am unsure how to copy a picture to make a realistic looking face. I have done some modeling, but have never tried to actually make the figure look like someone in specific. Any help would be greatly appreciated. I want to make sure I can do it before I agree to take the order.

TIA!

I'd go with RK and modeling chocolate, for the base and then cover it in fondant. Try to focus on the main aspects of the face, and slightly accentuate them, like in a caricature, but very slightly.
It may be handy to have a scaled sketch of the face proportions!
Good luck