Once the drawing is transferred to the canvas or board, the next step is to paint the background. I use lay frisket film down over the whole board. Using a very sharp exacto blade, I carefully cut exactly along the subject's drawn lines. A light touch is best; pressing too hard will cut the board, pressing too soft will not cut the frisket enough. Pull the frisket away from the board on the background areas you want to paint. Work from farthest back towards the foreground when you paint. Lay out your reference pictures close by so you can refer to them while you paint, to obtain the most accurate rendering of your image.
Remember when painting with airbrush that the colors are transparent, and layering different colors over each other can give different effects, and become darker the more you layer. For this reason, do not paint too darkly at first.
A trick to keep the paint from being pulled off by the frisket is to spray Workable Matt Fixative over the painted areas, letting it thoroughly dry before applying the next step of frisket film.