This is going to be a great render, one you'll be proud of when finished.
The undergrowth is excellent! And the grasses at the shoreline are a perfect fit!
Maybe some interesting, hand-placed group of rocks somewhere in addition could be a good idea!
Now, from a lighting perspective you image needs 2 things: more exposure, and less saturation in the atmosphere. Try setting the color of the background object anywhere between 0.25 and 0.5, which will not only give the atmosphere a less saturated look, but also help with global illumination. Really, :-) give it a try!
Cheers,
Frank