It's a good start. I would change the clouds to larger feature size (density fractal) and see what happens. For testing the terrain features, better disable the clouds temporarily (faster). Where would you want some glossiness? You can use the reflective shader, default shader or water shader for reflections. For a wet beach for instance, use the reflective shader but disable ray traced reflections (which make it act like a mirror and is really nice but adds to render time). Restrict that reflective shader to the height of the shore, near water (lake) height with a distribution shader. You can add a surface layer without color at the end of your line of shaders, mask/blend it by a distribution shader with the appropriate min and max heights (final position), and add the reflective shader as a child to this surface layer. Before the reflective shader (on top of it), you can add a color adjust shader with the gamma set to 0.8 or so, which will darken the wet area a little.
