Prepare your airbrush gun and paint. Read the owner’s manual, instructions and warnings thoroughly before beginning. Each airbrush will be slightly different in its setup procedure.
Choose an area to designate as your light source. For example, the upper left corner of your paper or canvas. Draw a small sun in that corner if it helps with the visualization.
Tape a template down on your work surface. You can buy a template or make your own with a thin plastic sheet and a craft knife.
Fill the paint reservoir with your desired paint and spray a base coat of airbrush paint for the basic shape of your airbrush design. Hold the airbrush nozzle approximately 6 inches away from your painting surface, as a 45 degree angle, to get a medium to wide paint coverage over the entire open template surface.
Remove the paint reservoir and add some white to the paint to obtain a lighter shade. Reattach the paint reservoir to the airbrush gun.
Hold the airbrush nozzle outside the perimeter of your template, at a 90 degree angle, approximately 6 inches away from the surface. Start to move the airbrush nozzle back and forth outside the template and start to spray, moving slowly towards the edges that are closest to your “light source.” Add just enough of this lighter color to highlight these areas that the “light source” would touch. Repeat this for any areas you want to highlight.
Remove the paint reservoir and add a drop or two of black or gray airbrush paint to obtain a slightly darker shade that your base color. Reattach the reservoir.
Spray the edges that would be considered “shaded areas” in the same manner that you added lighter shade.
Thoroughly clean your paint reservoir and airbrush gun according to the owner’s manual instructions.