1. Being there, the locations which things happen. Great locations allow high chances of encountering great stories, scenes which you try to capture.
1. Content/story - it always start with a subject, a story or something that catch the attention.
2. Lighting - this adds drama to the photos. But there isn't really any particular rules to what kind of light to apply. Make good use of back light, front light, side light, top light to enhance what you like to present. At times, back light is used to enhance 3D-ness, but sometimes if a compressed effect is desired, then front light could be better. For landscape photography, it's generally better to shoot in early morning or in the evening, because there's more drama during these times, but sometimes an over-cast sky is dramatic too, so it really depends on the mood you want to present.
3. Harmony - Firstly, harmony in composition. As a general rules, try to balance the subjects in a harmony way. But sometimes a skewed composition can enhance the visual effect. Secondly, harmony in subject types, try to keep subjects in the photos which relates to each other or the story. Thirdly, harmony in color, the color of a subject in the background for example, can either enhance or distract the main subject or doesn't fit the whole scene, try to avoid if possible.
4. Execution - As a general rule, try to be strict before pressing the shutter button, this takes patience. Ask yourself whether this picture is good enough, is it better if i move closer? is it better if I wait for the subject in the background to move away? And then, try to capture at the Defining Moment like what Henri Cartier-Bresson did.
With practice, these come naturally. Hope that helps.