One way to isolate a subject is to get close and make sure other objects around the subject are out of focus. Another way to isolate a subject is to use negative space. Basically this means having empty space around the subject, which means that there is nothing to distract the viewer. In this case I spot metered off the leaves, which were the brightest objects in the scene. As a result all of the other leaves and brush behind the subject are dark and thus not visible.