I would advice conservative interview style clothing like a suit in conservative colours. You just can't go wrong with that and everything else is a risk.
Hair tied back is fine, just make sure it looks tidy and stays like that for the day (check in mirror in your breaks).
Same counts for make-up. Again, go conservative, nothing too funky or like for a night out. If you usually don't wear make-up I would recommend to put on a minimum anyway as it's required for the job.