Do the background before you put too much work into the buildings. A background has a lot of impact on how the rest of the colours and details look. At the very least, put in some solid colours that represent the major parts of the background.
It looks like you're using a bunch of blow effects, but they don't really read. Try using some solid colours to show the illumination of the bricks, window frames, etc from the windows, then soften them up later if you want to. Don't start with complex things like gradients, they're just going to make it more difficult to see your more fundamental problems and to make edits.
