Your clothes should be plain and simple, not loud and busy. Glasses If you wear glasses, it would be helpful if you could wear a pair with empty rims for the day of your appointment. This would be useful as glasses not only catch light reflections, but also can deform the face-line.
Contact lenses are no problem.
Also bring one complete outfit. White turtlenecks or sweaters are also good. Knits photograph well, as there are fewer wrinkles. Bring several nice, simple dresses too. Slacks are easier to work in, but not required.