Creating a successful landscape image takes a variety of factors, including good technique, solid planning, a knowledge of lighting, and more. Composition is one of the most challenging aspects, and it takes a keen knowledge of what to include in the frame, what to exclude, and how to position them all. If that is something you find yourself struggling with, check out this fantastic video tutorial that will show you some solid advice sure to help you improve.
Coming to you from Christian Irmler - Landscape Photography, this great video tutorial discusses how to decide what to include and exclude in a landscape photo composition. By far, I think the most commonly overlooked part of the frame is the edges. It is easy to become overly focused on the center of the frame and miss something like a tree branch creeping into the edge of the frame, and while that might not seem like a big deal, once the eye catches it, it can pull the viewer out of the frame, which really upsets the balance of the frame. Be sure to do a check of the edges whenever you are about to press the shutter. Check out the video above for the full rundown from Irmler.
And if you really want to dive into landscape photography, check out "Photographing The World 1: Landscape Photography and Post-Processing with Elia Locardi."