Photographers that want to improve their portfolio of images should treat the background of their subject just as important as the subject themselves. For example, whenever I take candid photos of people, regardless of what the subject matter is, I try to infuse what is going on behind the subject and blend it to tell a story, therefore adding visual significance to the whole composition.
In the photograph below, taken at a Splashes of Hope event in Frederick, MD, I was conscious of the visual elements in the painting behind the artist. By using gazing direction, lines of continuity, and juxtaposition, the subject (the artist) is part of a story, not solely the primary focus of the photograph. Henri Cartier-Bresson was famous for using this technique in a lot of his pictures and is most evident in his series of portraits.