I spent a lot of time focusing on lighting, materials, and atmosphere. I tweaked the lighting, played with some post process materials to sharpen the scene, played with fog materials in cones going through the window with the pink neon sign and from the lamp, a trash material, created two vertex paint materials, looked into transparency and glass materials, etc.
I also made some new models, mostly small set dressing type of stuff like books, binders, folders, bottles, a plant, a new desk chair, picture frames, and also card. I also textured a lot of the assets already in the scene. I also spent some time creating simple building facades outside the window.
The trash material and it in the scene:
The vertex paint material:
I made the scene black and white to get a better sense of the values to help with lighting:
The scene at the moment with updated lighting: