Big City Lights - Creative process
I create 'The Big City'- series in Adobe Flash CS6, my all time favorite editor for vector graphics. Most of the time I start out with a few simple shapes and lines that I combine into larger, more complex structures. While working on the composition of elements I often use only outlines, just to get an idea how elements are stacked on top of each other.  
Each illustration is first created in grayscale. I use a lot of gradient fills to add highlights and shadows. In the final stages I also add serveral layers of half transparent gradients fill to add depth and athmosphere. Finally I export the illustration as PNG file and import it into Adobe Photoshop as 'Smart Object'. I use 'Smart Filters' > 'Add Noise' for the filmgrain effect, and add color by adding a adjustment layer 'Gradient Map'. I make the final tweaks using a adjustment layer 'Brightness/Contrast'. 
In a few cases I used Blur Filters in Adobe Flash to add an out-of-focus effect. I also use Blendmodes 'Overlay' and 'Multiply' to add more depth to the shadows and to enhance the lighter parts in the illustration. It all depends on the style and athmosphere I want to create.
thank you