Leave your subjects some space around and don't imprison them in the frame. Each side of the frame is a dead end for the viewer. There is nothing outside the frame. The photo is always within. If you leave some space around it is much easier for the observer to linger around the photo. The space is like the moat of a medieval castle which is difficult to overcome. It gives your subject the breathing space it needs and keeps the viewer inside. I have somtimes the feeling of claustrophobia when I look at (especially but not limited to) tele lens photos. Tight cropping, lots of bokeh, no space. There is no music without the little rests in between the notes and there are not photos without space around the subject of interest. The shot to the left would be less pleasing without the pavement at the left. I see a lot of photos with a dominating out of focus area. Something like f1.4 and close focussing. Boring. I personally feel that bokeh is much more pleasing when I can still recognise something in it. If it's totally blurred it a dead space to me. So, leave some space around and fill this space with something what's not overly distracting and take care it not a dead space.