My friend is a wedding photographer and a former runway model. She actually has a very good feel for dressing up something simple and she usually looks stunning in anything. I'm sure that she and I can come up with something appropriate that also fits into her comfort zone. I just needed to reassure her that she did not need to go out and buy a fancy gown.
One of my favorites is a "collar" made of mesh and then heavily beaded. It fits over the head and is about 12 " long all the way around. It makes even a very plain top look very dressy. WIsh I had bought more when I got it, as the price had tripled when I went back to get one for my sister! Guess they caught on.