First of all, I doubt that anyone can "enhance" the colors of nature, but what I meant by the title was how to enhance colors in your camera or with an editing program after the fact! Nature is perfect. No argument there. But you can get closer to sharing your vision of what your eye sees by using a couple of techniques.
The first is using a circular polarizing filter. These have been around for a long time, and do a great job of enriching colors, removing glare, and adding a bit of contrast to the whole scene. Polarizing filters work best when the sun is at roughly 45-90 degrees from your subject area. Typically, the outside of the filter can rotate 360 degrees so you can "dial in" the desired colors of sky, fields or water.
In this photo, I used a polarizing filter on a 70-200mm lens in late afternoon light. The sun was setting to my right which was perfect for the filter to do its job of transforming the colors, bringing out the vibrancy of the soy beans and sky.
The second technique I use to bring out nature's colors is to add contrast to a photo in Photoshop, Lightroom or any other editing tool. Many times our camera's sensors tend to "wash out" particular areas of the image, especially when the light is strong, so that an overall hazy glow seems to hide some of the colors of a scene.
Adding a little contrast darkens the overall image, thus bringing out colors a little more and defining the shapes and objects in your image. Adding contrast is probably the single most used technique I use consistently. Almost every image I've ever created improved a bit by adding a touch of contrast. Contrast is definitely something to think about when editing!
And of course, all this doesn't matter if you're not out there exploring!