1. Keeping it limited to warm palette, I painted in the ground and the sky. Used texture brushes and smudged to create some noise.
2. Started sketching in the mech using a hard edge brush at 100% opacity. My main goal here was to create interesting negative space since if I keep the shape solid it would feel less mechanical..
3. Using the lasso tool I traced the sketch in to a more clean organized shape. I layer masked the silhouette and did a gradient fill light to dark from top to bottom. Since the gradient fill established the mid value I proceed to indicate the light and shadow using round brush and photo texture (soft light layer)
4. I color dodged where the sun might be and changed the silhouette to show a soldier riding the mech. I added highlights and glows using color dodge as well.
5. I painted in the stencils and small details. Added some dust. signed my name and Done.
I kept the layers very simple 4 layers all together - background layer, silhouette layer (I link layer mask to keep the painting inside the silhouette), color dodge layer, and dust layer. Hope you guys find this to be helpful.