If you are interviewing with a firm that has a reputation for being more old-fashioned or stuffy, you may want to opt for a knee-length skirt suit. Many firms, however, including most of the firms on the West Coast, view classic pantsuits to be appropriate interview attire. Like men, I advise my female candidates to wear suits that are more neutral in nature. Black or navy is always a good choice, along with a solid collared shirt.
Please keep your jewelry to a minimum and your hair tidy. Make-up for women should also be pretty minimal. In regards to shoes, a classic closed-toe pump is always a good bet. At times, open-toed shoes can seem too informal or inappropriate for an interview, so do not go this route. I also tell my female candidates to bring a briefcase instead of a purse, as I think this looks a little bit more professional. It is also practical to bring a briefcase, as you can safely and neatly store extra copies of your resume, transcripts, writing samples, and references in it.