Before you take a picture it is a good idea to have some concept in mind that is intended to be communicated. Once that is identified to yourself, your self-chosen job is to reveal that idea as clearly as possible. Most of the really important things to do are done in the moments just before the exposure is made, because it is at that time you have the greatest control over what is going to be revealed in the final photograph. Once you have the idea in mind, it becomes necessary to find lighting which will reveal your idea most clearly— that includes the light source and the shadow source. The black light is just as important as the visible light because it gives the photograph its modeling and controls the contrasts. Moving the camera’s physical position, so the intended objects are revealed and the unwanted objects are outside of the field of view, is easily done at this time, but difficult to accomplish by cropping or cloning out later. Waiting until the right expression passes over the features of the person or object is critical at the moment, because little can be done in the lab to change the expression of the model. Some expression changes can be made but they require considerable skill, and probably will look artificial unless done by a master painter. While making the exposure the photographer can exercise maximum control over the symbols that will be seen in the final photograph, and these are controlled by pre-visualizing just where each of these symbols will be a few seconds before the exposure is made, so you can be in the right place when they all come together.
In the lab, which nowadays means when manipulating your photos on a computer screen, there are some basic considerations which need to be made. Ideally the full frame of the photograph will be used; however, especially when shooting fast moving subjects such as people, it isn’t possible to maintain the frame. Unfortunately, that means that cropping will probably be used in the final rendition of a photo of fast moving subjects, but don’t crop in too close too soon, because it may be possible to clone in background materials at 100% density into the final area, which avoids duplicating pixels in the picture. Overall color intensity and color temperature can be adjusted early on, because it will help you to see the picture, but it is also one of the last things to be done to balance the final picture. Once you have a good idea of the edges of the final picture it is time to clone out distracting details by covering them up with appropriate neutral parts of the image from outside of the final print, if possible. Also, there may be utility lines and other things which ruin pictures and are legitimate to clone out of everything except for legal documents. I am not enthusiastic about cloning out personal imperfections, because they are what give individuals their unique qualities.
Then come the subtle judgment calls which are necessary to make a good picture better. This is where the artistry of seeing what is needed to reveal the original idea at its perfection comes into play. See my article on Norman Rockwell, the American magazine illustrator of the 1920s-50s. He was a master at finding the choicest examples of typical scenes of American life and revealing them through multiple details. He did hundreds of illustrations, and so it becomes possible to see just what he was doing. That makes his work become cliché and trite after viewing a great many of them, but they do illustrate a very workable method, which is worthy of close study. As a rule, if something doesn’t drive the message home it is a distraction, although considerable material in the background might improve a picture if it gives context. One trick when viewing a photograph is to cover up potentially extraneous material with your hand or finger, and observe if that helps or hinders the intended message. Another is to view the picture at different sizes, which is very easy to do on-screen by making the resolution smaller. Adjust the picture so it looks good at all sizes, but make it look its best at the size that it is intended to be viewed. A really complex picture might look great at a very large size and poor at a postcard size, and vice versa with a simple subject. It seems that most viewers of photographs these days expect only a single revelation from a single subject, but this can be countered by having complex subjects presented in a large format. Some artists of the 1960s were playing with this idea by intentionally making super simple subjects really big, but that is the art of contradiction, which sometimes works.
Another easily done trick in Photoshop, to help understand what is in a picture, is to take a copy of a picture and run the numerous controls out through their adjustments to their extremes. Go one at a time to over contrasty, to over lightened, to over darkened, to over flatten, to over colorful, to over sharpened — the goal is not to show these extremes to anyone but to help you understand what is actually in the picture. That process makes it clearer what needs to be emphasized and what is to be suppressed. Some artists like to turn their paintings upside down, because it helps them to understand the relative weights of the composition better, and now we can do that instantly. We can mirror the images, and flip them too, all of which helps us to better understand what is actually eye-catching about a picture. Warping the picture in many different ways gives you a broader experience of what is actually there, and the various emotions available to be explored. It is the combination of many little things that makes the final picture.
Nothing should be included that doesn’t belong, and nothing should be missing that should belong, and it is the image maker’s responsibility to bring all of these many factors into perfect balance.