Start now, think later
Staring at the simple render you might feel scared and indecisive ? so silence the voices of uncertainty and just throw something on the canvas as early as possible!
The best way to start in this case was to throw a background onto the canvas, so I quickly added a ground plane to establish the perspective and depth. Then without losing too much time, I threw various elements in, re-using the low-poly assets from the game prototype just to remove the flat space around the character.
Filling in the background with low-poly assets from the game
And then a magical thing happened! My eyes locked on some of the messy 'pixel puke' on the canvas, and decisions about how to carry on spontaneously came to me. I visualized a steamy/dusty indoor space. The 'throw then think' methodology was starting to pay dividends.
Elements thrown in to create the dusty scene
Light it up
The next step is to define the light sources. Because I knew that I wanted a steamy environment, I actually indicated them like volumetric lights.
Creating and position the first lights
Once I knew what my lighting would be, I then cast the shadow of the character on the floor. To avoid painting it, I rendered something approximate in 3ds Max and added it as a pass in Photoshop.
Also, since we touched on the topic about shadows, something you should not forget would be to paint contact shadows on important areas, such as where the character is sitting on the ground plane. Without them you risk making the character seem as though it is floating instead of sitting firmly on the ground. I would have painted an entire AO pass if the time allowed it.
Adding in appropriate shadows make the scene more convincing