"An old saying in photography has it that -- "If your photographs aren't good enough, it's likely because you aren't close enough". This is often misunderstood to mean that one should be shooting with a long lens, or just doing close-ups. Not so. What is meant is that any photograph is of necessity about "something", and it is the photographer's task to hone the image so that it contains, to the greatest degree possible, only that which the photograph is intended to be about.
There is no magic bullet when it comes to cropping. It is an esthetic decision and therefore will be based solely on the photographer's creative judgment. Nevertheless, there are usually factors which can be considered and discussed somewhat objectively..."