Next step, work on the Background, I filtered the sky texture in Photoshop to make it more painter like with a smart blur. After, I played with hue-saturation and levels to equilibrate the palette with the lighting of my scene

To add more depth to the picture, I faked a fog with a cloud texture I used in transparency. It better than only using a simple fog, it fake the humidity growing from the vegetation in the early morning. I colorized all the picture in the same tones and decreased the contrast, the most important is to keep the brightness in the diffuse color and adjust the opacity (alfa channel) opacity adjustments on the alfa channel

The atmosphere is coming! Fog to add the depth, adjust the light direction with the texture of the Sky, of course you can "cheat" because the Idea is not to be realistic, but to do an illustration! I used several omni lights to enhance the lighting in some parts of the background because the direct light didn't light the mountain nicely. Its also good to adjust the colour of the fog and "faked fog" with the lighting of the scene, even if you use a blue ambient (sky colour) you want to feel that the atmosphere is light by the sun, so it can be better to use the colour of the main light with less saturation, but it's not a rule.