I can easily do a tutorial for this. I have created a template in Photoshop which makes it pretty easy (though still time consuming!) I have created several different layers and then set the colors and effects that I use within that layer. That way all of the maps that I do like this will end up looking the same, so if I want, I can later stitch them together for one massive map.
As I start to work on the next map, I will do a tutorial for it, and post it here.