First of all, artistic skills cannot be taught, so do not get disappointed too fast. You have to learn how to "see" things rather than just watch or copy. If you take a photo and then give it to 10 people you will get 10 different interpretations and approaches meaning 10 pictures!
If you ask a photographer how to photograph things, he will certainly describe you the technical details, but he will fail to make you feel the same he felt when he released the shutter. These things are rather felt than taught.
Technical data is supposed to be easy (?) to learn, everything else is the difficult part. Every person "sees" different things in a scene. He is drawn to and composes different frames in his mind. This is the beauty of photography. In fact one of the exercises that is famous among the study groups is to take 100 clicks (photos) locked in a bathroom. Yes you heard me 100 different photos in a single 2x1 room. This is an opportunity to learn how to "see".
Every photo has to have what is called "balance". Balance is the order of things inside the frame. Where the eye begins its journey and where it end its quest. After that, the mind tries to decide if it likes the picture or not. If it does, the decision comes fast. If not, the search continues until it finally gets disappointed. Both decisions take a couple of seconds and they all depend on balance of color and composition. If it is a smooth transition, we like it. If it is disrupted by distracting objects or things inside the frame, we don't. As a general rule simple things carry strong emotions.
Light plays its part with the objects in the frame. We can all see dark or light places and we can compensate our eyes for them in real world. But when using a camera things can change dramatically. You see, imagine light divided into 8 parts (or stops). Our eyes can see the whole 8 stops, but cameras can only see 5. Your decision is to select which 5 to record. So much for exposure! If you want to artificially "increase" the stop range there are several techniques such as Dynamic Range Increase (DRI), or High Dynamic Range (HDR) which can sometimes alter the colors so badly that the image does not appear real.
There are several different ways to layout the elements in a photograph. Filling the frame is one of them, but the most important is the "rule of thirds" from which the "golden mean" derives. The main purpose is to provide a path for the viewer's eyes to follow throughout the photograph.
Find a clear center of interest, something that captures your eye and avoid distracting shadows or elements. Keep things simple and straight.
Fill the frame
Robert Capa, a WWII photojournalist said it best "If you're pictures are not good enough, they you're probably not close enough."
Say it clearly
Try to avoid anything that would distract people from your main subject. Focus on the subject.
Search for captivating objects
Look for repetition or patterns, diagonals and lines which are always interesting. Scan for contrasting colors and shapes.
Depth of field
Use the aperture to create depth. Make objects in front and behind your subject a little out of focus. This will isolate the subject from the background and focus attention on the subject.
Most people look at the lighter portions of a photograph first, then the dark areas. Focus on the bright areas having texture.
Vertical and horizontal lines are not appealing, diagonals are. Psychologists say that instincts go back to our caveman days. Diagonal images are visually more interesting than vertical and horizontal.
Vertical lines are all about power, strength, and height. Horizontal lines emphasize stability and width. Diagonal lines express dynamic energy. Curving lines express sensuality.