At the few weddings that I photographed before deciding it was not for me, I wore a suit and tie. I felt that dressing appropriately was part of appearing to be a professional, along with behaving professionally and producing professional results. For the pre- and post-ceremony photographs, and while working at the reception if the hall was warm, I did remove my suit coat. Some wise person once said that you can never over dress for an occasion. If in doubt, dress up!