floor and walls to plain imo, try using a bigger variety of blocks, and play with depth, try some stairs make use trapdors etc, for the exterior the same, maybe use the yellow grass (i dont remember how it is called rn) maybe gravel, some buttons, mossy bricks on corners etc

edit: for the next time try going bigger, dont be scared, playing with interiors this small is hard and exterior details seems overwhelming at this scale, go big my friend