Again, still very much unfinished, but here's some of the next stage in how I work! For those who speak Photoshop, what I did from the last step to this one, was add a layer on multiply, and used the paintbucket to make the entire layer blue. This is a night scene, so it's an easy way to darken everything as it would look of shadowed at night.

Also started adding in the highlights on another layer! I used a light blue to start adding in the "moonshine"...;) Once I finish highlighting everything, I'll be moving on to add shadows. But I'll leave it at this for now!