A little bit of graffiti art history.
We had various methods back in the day to get our message across. A sketch like this, would be drawn out on a Friday, and painted/bombed up on Saturday. It might stay in my back pocket for a day or two, notice the folds? Usually my sketches were done with a standard, regular pencil, one I had laying around, nothing fancy, and a piece of paper. 8.5x11, back then I’d draw on anything. One other thing, see the little notes, the writings? All color ideas, the three basic areas. Your “outline”, here it’s Jungle Green, your “fill-ins”, here it’s Purple, Yellow, Hot Pink, Light Blue, Almond, your “background”, here it’s Black. Everything in your back pocket.