Well, the light in your render is superb. What I would do is make more variation in grassy areas; different tones of greens and ochres/greys, and perhaps also mix in some more species of trees and shrubs to get more of an ecosystem. More/denser woods in the valleys perhaps, thinning out in places.
And the foreground is too simplistic; if you could add some large and smaller fake stones there, it would look like you're standing on a rocky promontery (if that's the word). You can localize the fake rocks with a simple shape.
It's worth working on your doodle anyway.
