Nature is a chaotic place. Our job as photographers is to create order out of chaos, to simplify and reduce things to their essence. Most beginners have trouble keeping extraneous and distracting elements out of the image frame. Many advanced shooters struggle too, trying to get too fancy and complicated. As Ansel Adams once famously said: "There is nothing worse than a sharp image of a fuzzy concept." Taking his advice to heart is an easy and effective way to improve your compositions. By keeping it simple, and including only those elements necessary to get your point across, your images will have greater impact on viewers.
Take, for example, the image above, which I made while deep inside Antelope Canyon (and which is the cover of my most recent eBook 10 Easy Ways to Improve Your Landscape Compositions). During the day, most of the canyon's interior is lit only by light reflecting from the blue sky above (creating blue and purple tones), and from light bouncing off of sunlit sandstone at the top of the canyon (creating the orange glow). This image is all about the juxtaposition of a few simple shapes and two contrasting colors. I carefully zoomed in to exclude any extraneous elements that might compete for the viewer's attention. Sometimes, simple curves and a splash of color are all you need to make an effective image.
I don't always like to keep things simple. Complex compositions are extremely difficult to master, and all the more rewarding as a result. But start off first by mastering the art of simplicity, and you will notice a dramatic improvement in your photography. Then, you will be ready to tackle some of the harder stuff!