I Start off with an image in mind, one that I have drawn once already in my sketchbook. It is fairly simple so I can sketch right on the wall, no need for any complicated grid or protector transfer method that I might use on a more complex paining.
Now That the image is sketched I am ready to start with the colors. For this image I used FLAME ORANGE spray-paint (great brand, affordable alternative to MONTANA or MOLTOW). As I put the colors into the image I am imagining a light source on the figure emanating from the top left of the image. This determines where I place the shadows, highlights, etc… Also notice the blue rim light active on the shadow side of GREMBLO. this represents a minor secondary light source shining a cool back light on the figure.
As the color stage progresses I am careful not to lose track of the drawing underneath. the drawing is my guide and is instrumental to doing the line work. I leave gaps in the paint were I know black lines will cover.
I do the thick black lines with spray paint, its important to note I am using a skinny cap. I save the finer line-work for my MONTANA black acrylic paint marker.