A photographs shape can affect its meaning. A photograph takes the 3 dimensional world and flattens it into a two dimensional image. The world is reduced to its basic elements. Line, repetition, color. With your camera take pictures of shapes that interest you. Explore why the shapes interest you, isolate the shape, does it suggest anything to you? As Edward Weston states of his famous Pepper #30 photograph “It is classic, completely satysfying-a pepper-but more than a pepper; abstract, in that it is completely outside subject matter.” With this in mind, compare his famous Pepper #30 and his image Shells to his other equally famous photograph Nude. He takes a closeup picture of the pepper, outside of its context, and minimizes the background to almost black so that we only see the shape of the pepper and the countours of its surface.
You can also use shapes as a metaphor as Warren Padula does in his photograph of a dairy aisle in a supermarket titled Mouth. Or you can make abstract compositions from peeling paint on a wall like Aaron Siskind does.