Tight to Rule #1, this one could be phrased differently : Make your subject matter clear and one only… As I explained in a previous post, ( here ) Photography is a substractive process in opposite to painting which is an additive process : You start from a white canvas and, progressively, you’ll add elements to your composition. Achieving a photographic composition consist in subtracting all disturbing pieces in the frame. Then, you will focus viewers attention to one clear subject matter.
Your images will be stronger because straightforward ! In this image, blurring the waves by a long exposure contributes in isolating the wharf since it becomes the only sharp area in the scene.