The first step in creating successful images is to consider the ways seeing differs from photographing. Understanding the differences will make it much easier to work with your camera and make you start to pre-visualise your image.
Let's assume that you are hiking in the mountains and see a majestic landscape in front of you, your eyes act as little optical machines to register the scene but all that you see is enhanced and interpreted by your brain. Hence some of the splendour of the scene is supplemented by your mind.
If you lift the camera to the same view, you will get a completely objective representation of the scene, without any intelligent enhancements. It has a much more limited range of focus, exposure, and composition than you do. The camera is just a little optical machine with no mind of its own. You might consider, yourself - the photographer - as the camera's brain employing different compositional techniques to add intelligent interpretation of the scene on paper.
The first think you immediately notice when you look through the camera's viewfinder is that the scene in front of you is cut down into a small rectangle with defined edges and corners. You are forced to compose the essence of the scene within these artificial boundaries. You can therefore frame the scene in variety of ways, creating images to emphasise different parts of the picture.
When we look at a scene we also have the extraordinary ability to concentrate on the main item of interest, despite the cluttered surroundings. We can filter any part of the scene that is considered as unimportant. The cameras on the other hand are not as selective as the human eye, and the photographers need to use a range of techniques to add emphasis to their images and to direct the attention of the viewer.
When looking through the viewfinder, train your eye to check for distractions in the foreground, midground and background. Always make a quick scan of everything in the viewfinder before pressing the shutter release button.
Other point to remember is that cameras do not have binocular vision that is they do not photograph a scene from two points of view. The images they produce are thus two-dimensional as opposed to three-dimensional as seen with the human eye. So when you want to show depth and distance in a scene you photograph, you will imply it with devices such as the use of converging lines , change of perspective, or changes in tones aided by lighting.
Our eyes are quite sophisticated and can make out details both in the dark shadows and brightly lit parts of a scene. The same unfortunately cannot be said for the digital sensors and films. They cannot cope with the same contrast and will not be able to record a clear detail in the highlight and shadow areas. It is therefore important to remember that the contrast that you see with your eye will be different to the one recorded by your camera and with practice you will be able to anticipate how your images will turn out.
While we are looking at an action scene dynamically, most photographs capture just one moment in time. You need to be alert to capture the peak of the action or to be able to make quick decisions in order to catch the decisive moment that sums up a situation or simple gives a good composition.