How you dress for an interview is your first impression during the process. It's a visual assessment to see if you are taking the interview process seriously and if you'll fit in with the company culture. Unless specifically told otherwise, you'll want to dress in business attire. Hair, teeth, facial hair, and nails should all be well groomed.
A conservative suit - a jacket with a shirt and tie paired with pants or a skirt in basic colors such as black, navy or grey. Finish the look with dress shoes, basic pumps or flats. Make sure they are closed toe and comfortable - you never know how much you might have to walk. Keep accessories like belts, watches and jewelry simple. Nothing tight or short. Maintain a classic look.