I'm assuming you're male. Please correct me if I'm wrong.
Conservative suit (2 or 3 button only), navy or grey (not black!!!), well tailored. White or light blue shirt, conservative tie--nothing cute, funny, or remotely resembling a Hawaiian shirt). Plain, cap-toe shoes, preferably balmoral and shined. Most places today will try to sell you these square-toe'd, duck-bill shoes. While popular, they are not conservative. Dress socks should match your trousers, belt should match your shoes.
Basically like this without the pocket square:
After getting the job, you should take your clothing cues from those who work there. Don't out-dress them (much), but definitely don't under-dress.