Right now it’s very boring and kinda ugly. How can I beautify the scene?
Needs a ton of post-processing. Under no circumstances put in any objects!
What kind of Post-Processing?
I’m joking. You are showing an empty scene with nothing but terrain and ask how to beautify it. Put objects into the scene for a start! How about foliage, characters, roads, buildings, etc.
PS: Sorry, didn’t mean to sound angry
You have a point 
Make the dirt orange instead of brown. Make the grass just slightly bluish, but so it still looks green. Find some nice semi-complimentary colors but also make sure you have some contrast in the value, not just the hue.
Add some sort of depth cue like fog or clouds.
Gras and Rocks, maybe even Trees
You can use a normal map, to add details onto the landscape, if you haven’t used one in the scene yet.