Updated post. Added new pics.
@Schmitzenbergh, I added a few changes as requested, however I haven't decided on a proper rock texture and a way to make the land around the lake to look realistic. Also, the background trees are affected by shadows completely (check 3rd picture). Is there a way to fix this? I know this has something to do with the direction light but I'm not exactly sure how to fix it.
I have only started adding more details in the map, so obviously try not to judge it too hard, just tell me what can be done better next.