I used the technique here by creating a separate clean layer and then using a specialized brush and painting a speckled design on it. I took that into blur and used the path blur to generate the color you see here. I used another clean layer and painted blue lines on sections of the doors and windows. I took those into blur as well. Basically, you can use paint to accent anywhere you decide and the blur will blend it. You can further use blend modes to manipulate what you want. I will use this method a lot and didn’t have to pay big bucks for it.