Multiple rings and dangling earrings are definitely don'ts. Women's hair should also be relatively conservative. An interview is not an appropriate time to show off your mall hair. Long hair should be kept out of the face, possibly pulled back with a clip. Shorter styles should be kept neat.
Many people forget about their shoes when they go on an interview.
Telford said shoes are an indicator of your work. Always have your shoes well-polished and make sure your heels are not scuffed. Morony said that in a conservative company men should always wear oxfords with laces.