Going back to the original question and the title of this thread, I realize that I never actually responded to it. Others have already talked about the usual components: the important factors of light, composition, subject choice, technical skills, etc., so I won't repeat all that again. Digital photography encompasses a lot of skills, ranging from shooting the image in the first place to how it is presented. Some people are more interested in the technical aspects while others lean more into the artistic elements. Some are happy spending more time with the camera and less time editing images later, while for others editing and utilizing sophisticated skills in retouching are the more appealing part of the overall process. Many people are somewhere in-between.
Some people prefer to stick within one genre or type of shooting and are interested in developing their own style, while others tend to try exploring different genres, different types of shooting with different types of lenses and focal lengths, and somehow somewhere along the way their style makes itself apparent without conscious effort. In the end, the goal is the same: to offer an attractive, interesting, sometimes quite compelling image. Many photographers may or may not produce images meant for professional portfolios or hanging in galleries, images which are outstanding and attention-grabbing, but most of us usually recognize a truly great photo when we see it.
I've been reading Bruce Barnbaum's excellent The Essence of Photography, a book which addresses much of what goes into creating great images. He also has authored The Art of Photography, another excellent resource. Both books are illustrated with many of his own images, some outstanding examples of landscape photography, but neither discussion is limited to that one genre; he talks about what can influence an image and these various elements can apply to any photograph in any genre or style.
Something which is alluded to within this thread but not really discussed is the significance of creativity, which can play a key role in an image, from inception to final result. What is creativity? One partial definition might be: a new way of seeing, looking at the familiar, an exploration of potential emotional depths within the subject, which in turn can evoke an emotional response on the part of the photographer and subsequently an emotional response by the viewer. Creativity involves innovation, incorporates curiosity, usually has a spark, an enthusiasm for experimenting, exploring the unknown, and often will result in an image which is indeed different, with impact which immediately captures the attention of those who view it.
One starting point is the subject matter. If the scene or the object or the living creature in front of the camera is not of interest to the photographer, why would any subsequent image shot of that be interesting to the viewer? The photographer, by choosing to spend time with the subject, is already investing some of his or her own emotional energy in it, and often will spend time visually exploring the subject with the camera and a lens or two to discover the inherent possibilities which lie within. From this comes the meaning of the subject to the photographer, which then is conveyed to the viewer, sometimes with dramatic impact. A rapport with one's subject from the very start, the photographer's own feelings and response to the scene or the person or the animal or the object, is key to what follows once the shutter button is released and an image is created. If the photographer isn't interested in what he or she is shooting, that is going to come through in the image, and a viewer will sense that as well. If there is genuine interest in, or even love, for, the subject matter, that, too, will shine through and usually evoke an emotional response of some kind in the viewer.
Creativity is innate within most of us but sometimes it takes time to develop and flourish. An open mind, being on the lookout for interesting subjects with potential of being seen in new and different ways and the passion and enthusiasm for photography itself can be a valuable contribution to one's personal approach to the art and science of photography and the creation of interesting images.