Look for plain backgrounds and avoid strong patterns or clutter behind your subject. A single subject against a plain background will stand out better and make a stronger image. You don’t want what is behind your subject matter to take attention from your subject. A plain background shows off the subject you are photographing. Having a plain background creates emphasis. When you look through the camera viewfinder, force yourself to study the area surrounding your subject. 

Emphasis is a principle of art which refers to the use of visual elements to draw attention to a certain area, usually a focal point, in an artwork.