A photographer called Andre Gunther published an article on his website about the ten most common photographic mistakes. Here's one of them:
1. Images are too cluttered (less is more) In Photography, less is often more. Before pressing the shutter, ask yourself what you first noticed in a scene that made you want to take this photo. Then try to isolate whatever you saw, without including too much in the scene. Otherwise the viewer will get confused and will start wondering what you wanted to show and why you bothered taking the photo in the first place.