Bring a portfolio case or briefcase with you to the interview. Make sure your hair is neatly groomed and your fingernails are trimmed and clean. Men should wear a silk tie with a conservative pattern. Dark lace-up shoes are best, along with dark socks. As mentioned above, a two-piece suit is preferable to a dress.
Many recruiters prefer suits with a jacket and skirt, rather than a pants suit.
Make sure your skirt is long enough. Be sure to wear pantyhose at or near skin color, and make sure there are no runs. If you wear nail polish, make sure it is a conservative color. Your hair should be pulled away from your face. Although suits are expensive, it is smart to invest in one or two good quality suits for interviewing.