The challenge of composition in landscape photography is that you can't control the location of any of the elements in the frame, only your position relative to them. This leads to some common mistakes, and this great video tutorial highlights one of them and how you can easily fix it.
Coming to you from Mark Denney, this excellent video tutorial details the compositional mistake of destroying the geometry of the scene in an attempt to find a more pleasing perspective. Some very common advice is to get low with your camera, as this changes the perspective from eye level, as we are normally used to, and can be used to emphasize different elements of the frame. However, if you evaluate the scene from eye level and are not careful you lower the camera, you can render leading lines or interesting geometric interplay between the various elements invisible, which can then undercut the effectiveness of the image. Luckily, it is an easy fix: simply be aware of the trap and double-check your photos as you change the level of your camera. Check out the video above for the full rundown from Denney.
And if you really want to dive into landscape photography, check out "Photographing The World 1: Landscape Photography and Post-Processing with Elia Locardi."