16: Boss your camera, don't let the camera 'boss you', i.e. you need to know your camera inside out, it's strenghths and weaknesses, and be able understand them without giving it a conscious thought.
For example canon 20D can generate quite noisy shadow detail in underexposed shots, you should be able to manage and compensate for this weakness without thinking about it.
17, Landscape photographers don't photograph objects, scenes, etc, they photograph light. So you need to be able to understand light, be able to interpret that light, and what it means for a photograph, For example most photographers know that shooting in that magic period between dusk and dark can produce images that can sing, but you need to be able to understand that light to make the best use.
18, All good images have a beginning, middle and end, and need all three to work, for example I have seen some reasonable sunsets posted, usually over water. These images have a middle and end, but no beginning, therefore don't work as well as they should. The author has (probably) been overawed by the glorious sunset, that any thought of FG interest (beginning) has gone.
19, Photographs are 2D, although we see in 3D, therefore you need to be practice seeing in 2D (previsualising), and arrange the composition to give a perception of 3d in the final image. For example, most mountain ranges look glorious, we can see them in 3d, the camera interprets them in 2D, so often look flat and lifeless. You need to be able provide enough visual clues/elements to give perceived depth (3D) this could be simply including a FG tree, using a twisting road to invite you into the image.
20...Ignore points 1-19 above, throw the rule book away sometimes and jump out of the box.
Canon 1DS MKIII,7D, 85 1.2L, 24 F1.4L, 135 F2L, 200mm F2.8L,50mm F1.4, 120-300 F2.8, 12-24mm f 4.5
Concentrate on equipment and you'll take technically good photographs. Concentrate on seeing the light's magic colours and your images will stir the soul. - Jack Dykinga