Henry Ford once said "Whether you think you can or think you can't, you're right." Although it seems unlikely that Mr. Ford had much time to do anything with photography; truth is truth, and it crosses all boundaries. If you want to become a great photographer; not just a week end warrior, your dominant thoughts need to be on what makes a great photograph.
If all the subjects in your image are of equal size, shape, or visual weight, with nothing being clearly dominant, it becomes very difficult for your viewer to know what to focus on. In a great photograph, things that are dominant have the most visual weight. They are the most important, powerful, influential elements in your image. Things that can dominate in a great photograph include: the subject, color, line, size, shape, or texture.
The subject is generally the object that you want the viewer to notice most. If you have a field of bright yellow daises for example, that will catch some attention. However, if you find that on one edge a spider has created a huge glowing web; and focus on that, then the daises only become background. By shifting your focus to the spider first, the viewer has a place to start. They may still think that the daises are awesome; but the spider acts as the first page in a great novel. It gives your viewer a reason to want to explore the rest.
If you have a dominant color you subconsciously have tapped into the viewer's emotional reservoir. Depending on their own past experiences, different viewers will have different reactions to different colors. Take red for example; it can be thought of as power, strength, or passion, but . . . it can also be associated with anger, violence, or danger. The emotional impact of a burning building with a woman leaning out the window holding a baby in her arms; will not be the same as a father and son roasting marshmallows over a camp fire. Even though both images may have a dominantly red or orange tone, the history of the viewer will greatly impact the success of the image.
Dominant lines help to create depth, but more importantly they lead. Face it, lines lead. That's what they do. Now if you're careful they will lead your viewer into your image; but . . . if you're not careful they can also lead them out of the image. They are your supporting actor or actress. They can actually be the main subject, but most often they are satisfied with making your subject look good. They also have a certain emotional impact. Think of the calm peaceful lake at the base of a snowcapped mountain, that's usually a horizontal line. On the other hand, visualize a tall powerful redwood tree, more than likely that would look best shot as a vertical shot to emphasize the vertical lines.
That brings up another important point. If something is suppose to dominate the frame that's kind of hard to do if your camera is in the wrong position. If you are shooting a predominately horizontal shot then its fine to hold your camera as normal. If you are shooting a vertical shot however . . . please turn the camera on its edge so it is also vertical. By not doing this simple thing, many photographers waist a lot of space and leave your photograph full of unwanted clutter that only detracts from your main image.
By having something dominant in size, you make things more real for the viewer. If for example; you have a picture of "The Narrows" in Zion National Park, they are very interesting in and of themselves. However . . . for someone who has never been there it is hard to comprehend these beautiful walls of red rock often 80 feet tall or higher. Now if within this shot you also have a hiker, you now have something for the viewer to relate to. Without the hiker, no matter how gorgeous this curvy canyon of massive red walls may be, it is impossible for someone to comprehend how awesome it really is. It would be like describing the Grand Canyon in Arizona as a really big hole. While technically that may be true, your idea of big and my idea of big may be totally different.
When you practice dominance in shape you are often dealing with patterns. Remember that when you repeat a shape one or twice it becomes more interesting; when you repeat that shape several times it becomes a pattern. A single daisy along the side of the road might make an interesting shot. Two or three daises gives your eye something more to look at; to dance from one point to another, but, a whole field of daises paints a whole different image! You can easily use this to show opposition as well. While a row of small balls placed in a semi circle might be interesting; it would be far more interesting if two thirds of the way back there was a block in the line up.
When you look to make texture as a dominant element in your photograph, you are taking your work to a whole new level. Whether it's the fluffiness of a newborn kitten or the glistening of a rattlesnake's skin in the desert heat, you can almost "feel" the emotion rising within you. If you can make some one have an emotional response to your images, you have a great shot. You may never see a photograph of a young sexy model dressed in a potato sack. Why? Because even though the texture may be interesting, it does not compliment the subject. Texture is another one of those supporting characters that make the difference between, "Oh, she's pretty." Or "Wow, is she hot!"
Great images don't just happen. When you constantly think about and remember the basic elements of design, the award winning shots are much more likely to appear. If you want to be a world class photographer, you must think like they think, you must see things like they see them. Ralph Waldo Emerson made this observation, "A man is what he thinks about all day long." You have the power within you to achieve greatness. Focus that power, focus your thoughts, and by all means focus your camera on dominance in your images.