Hey there! :3

Firstly, terrain. I think you have a few too many leaves in the ground. From what I can tell, you wanted to replicate like a jungle area, but it looks a bit too 'easy'. I would reduce some of the leaves in the ground, and use more of a palette, with clay etc.

Secondly, organics. Your tree is really nice, but the leaves and branches need work. You need a lot more branches; large and small. You would also benefit from using a larger brush, with a high air percentage in the brush
Eg: //br sphere 10%leaves,90%air 5
Search Plutouthere on Youtube and watch his God Tree tutorials. I think they'd really help you out!

Lastly, structure. The structures you have are really nice, but a couple more would be cool! Also, a little improvement to the detailing/depth on the walls.
Use a frame: https://imgur.com/ONsoRxh
A frame is when the outer blocks are one layer out from the wall. This creates basic depth - it'll also make it easier to detail. You could use wooden stairs and trapdoors etc for detail design.

Good luck!
- Dutty :3