If it helps, I would always recommend using some reference. For instance, aside from just colour and some vague shapes there is actually no detail of the rock looking like rock, maybe experimenting with some textured brushes would help that. Same goes with the grass patches. A good indicator of scale is always trees, and while you do have some small ones right at the top (ngl I didn't notice them until I looked really close for this feedback), it could benefit with many more, perhaps on the side of that arm, shoulder and head.