either more gradation or group of objects that have different local value and colors. Another thing is do not get caught up with those two statues. They are far away that you should try to make the scene work as a whole. Also, start to paint with zoom in to have more various brush stroke. When I zoom in there are too many similar brush strokes. The gradation in the middle ground sometimes can be achieved by couple big fat brush strokes than lot of small strokes.