This painting requires that the goal is kept in mind, that being shadows and light leading up the path to the focal point where the trees meet the sky. Sounds easy, I know you are up to the task. Bring some lights in from the left and keep the brush work lively and varied. Mix your greens on the paper to start with and then on the palette for the darker pieces.Use a nice cool blue for the sky brushing with a larger round brush, make the emphasis on the middle of the sky where the trail ends. Put a yellow wash down and then blue on top for the foreground, Of course vary your yellows and blues, I know that is what you were thinking of doing.Brush a yellow wash for the base of the trees and a variety of blues over top of that to make the greens.Paint the foreground with darker greens and red oranges for the foreground. Consider the angle of the ground and leave lights for the patches of sun.details of foreground flower weeds. Used the tip of a round brush and little water and flick the tip off of the paper.Paint in the trees with a liner brush and remember to not paint the trees too dark of they will jump forward. Keep them back in the canopy. I try to make the trees about the same value as the darkest part of the tree canopy.