Virginia Beach Photos - Norfolk Photos

I've just finished updating my website, and have added many new photos of Virginia Beach, photos of Norfolk and other areas of the Commonwealth. Now if I could just figure out why my page ranking keeps changing, and not for the better! Can anyone explaint his to me? I've triued using keywords and keywords phrases (combination of two or three words) that I thought would help point search engines to my website. So far, that's not happening! Any advice is welcomed!