I have mostly used the Terraficta tool as is. The only thing that I did extra was to use the brush tool to spray different shades of green and brown for the background(ground surface). I also expanded the default size of their templates to fit the drawing that I was using.

Terraficta is a great add on for Photoshop, it has all of the layers predefined with the effects that they need to get the look that you are looking for.