Fantasy cave

Hi I just finished my last work and I know I have log way to made my projects looking better.
In my opinion my biggest problem is how to fill all view and to how made it more realistic.

Here is my last projeckt.
Few fings added in Photoshop:

And here is raw render:

If u want you can also check it on ig:

If you have some tips (your own or some tutorial on yt) please write it.