I feel that the paper's edges are too bright; maybe aim for an in-between color of those two tans through dithering, with it leaning a little more towards the darker shade. Also seriously consider dithering the picture into the paper along the edges, like a sketched-out sort of effect.
For such a small landscape, AA-ing is your best friend.
I understand that this is a WIP and that you might still be laying things out, but please don't skip this step! It would do wonders on that road.
