What can you compose coastal shots and avoid having uninteresting sky or expanse of water

The thing that can help you compose coastal shots and avoid having uninteresting sky or expanse of water is the rule of thirds.
It is something that is often used in painting, as well as film design, and photography. It means that each image should be divided into 9 equal parts and that the most important objects should be placed at the intersections of those parts. I've attached an image to show you what I mean by that.