Photography is a subtractive process. Upon looking through your viewfinder you must decide what elements to exclude before pressing the shutter. Distractions, mergers, bright spots, color conflicts, etc., need to be eliminated to direct the viewer’s attention to the intended subject. If the end result is chaotic and confusing, the picture will lack strength and impact. A way to prevent this is to simplify the composition before you shoot.
Many photographers see only the subject and ignore the peripheral areas surrounding it. A tunnel vision phenomenon kicks in where the photographer concentrates solely upon the key element of the composition, and he or she becomes oblivious to what's directly to the side or behind it. Learn to study the entire viewfinder before pressing the shutter.
The point at which this axiom become part of my awareness occurred when I was visiting the Galapagos Islands years ago. Our guide told us we’d see hundreds of sea lions so when we beach the landing craft, do not photograph the first one we see as it will more than likely not be in a great position or in great light. We all nodded our heads OK. Guess what the entire boat load of photographers did as soon as we landed—that’s right—we went nuts photographing our first sea lion. I threw away every one of those images! Rather than becoming a victim of the “First Sea Lion Syndrome,” learn to study the viewfinder and press the shutter only after studying everything the lens sees.