There are certain things you start to pay attention to when you take lots of pictures. When you feel like you have gotten the aperture right and the shutter speed right. Your exposure is good. Now how does a good photo become a great photo? It's attention to detail. If you want your subject to stand out you pick simple but picturesque backgrounds. If you are taking snapshots on the fly and you can't control the background then you shift your subjects to make sure that there is no tree growing out of their head or a pole! Seems simple right? But if you don't pay attention to the small details you pictures look cluttered and your subjects get lost. Or worse, they look laughable because some object is protruding at just the wrong angle! I try to pick simple backgrounds; a row of tall bushes, a brick wall, the beach when no one is there. When you have control over your environment it eliminates anything that might get in the way. Happy Shooting!