Secret Desert Entrance

I like the simplicity of the scene, there are a few easy wins to improve it.

Even though the sand is flowing in the one direction, it looks noisey from this angle. Have it come towards the camera more, bring down the tiling and soften the normal map

Model the building as a whole, all sides. It will give your building a more solid, credible appearance. You don't have to add detail, just have the overall form.

For instance, the rock holding the door is too short and 2D looking. Put a large rock behind this one so that it fills the building out more and looks less like a prop from a film set.

The composition could be more balanced and less symmetrical .  The heavier volumes are on the left, push them closer together.  The rock on the right seems  isolated and the small rock on top looks like it's going to fall down, it is distracting instead of interesting.

It's always worth modelling small clusters of rocks, say 3 kinds.  Have the sand go a little further up the structure, smooth out the sand below a bit and place some small rock clusters at the base of the larger rocks, just a few placed in clusters and leave big gaps between the clusters.

Have a look at how old asymmetric churches are balanced and experiment with the pieces you have here, you should be able to get great results with this cool little kit you've made. I know this is mostly a cliff wall but if you improve the composition of the rocks you could make lots of cool looking tombs. Throw in some cute palm trees and you could have a lot of fun improving your composition skills.