I think I was initially influenced by the Hudson River school of landscape painters.
As I tried to understand what I liked, I looked at a lot of paintings and photographer's work. Both mediums deal with line, balance shape end visual tension. While photographers deal with the light that they have, painters crate their own lighting, shadows, highlights. One can learn a lot about lighting by studying famous paintings by the master painters.
Painters start with a blank canvas and add elements to achieve their vision. Photographers start with all the complexity of the world and sky and eliminate elements to achieve their vision. In both cases the key is understanding the affect of each line, texture and shade. Find the key elements, find the angle that puts these elements into the best relationship with one another and minimizes disharmonious elements, then try to expose film under the best lighting condition to make the elements work together.
There are two photographers I really like because of the way they accentuate lines, Freeman Patterson and David Muench.
The best books I have found to teach me how to frame a landscape photograph are how-to books on Japanese garden landscaping. They help me understand which elements have strong visual appeal in which kind of relationship.
