step 1 of 5
Only photoshop cs4 extended used in this entry. I drawed here a simple shapes with pen tool and fill them with colour.
step 2 of 5
Here i brushed light bulbs and walls with floor... Used low opacity natural brushes.
step 3 of 5
Here i used low opacity burn and dodge tool to make same colour dinamycs to make shadows, higlights and fixed some edges. And painted rougly trees.
step 4 of 5
Here is little more dodge and burn tool and kind a window draw...
step 5 of 5
At the end i just fixed colors which i think look better.
Final result
