To keep designs even and symmetrical, use a stencil to paint shapes and patterns on each side of the helmet. Cut the desired shapes into a sturdy piece of card stock or thick paper, and tape the stencil in place before applying paint without the cutout. Once the design is painted, allow the paint to dry before carefully removing the stencil. Create straight, even lines by taping masking tape on either side of the area where you want the line. Paint over the exposed surface, and remove the tape as you would a stencil.
Dark and neutral colors may more adequately reflect an individual wearer's personality, but these are discouraged in applications where safety is tied to visibility. For motorcycle and bicycle helmets, use brightly-colored paint to attract the attention of other motorists. Fluorescents, whites and other bright colors are ideal to increase visibility. For night time use, highlight existing designs with reflective paint to draw attention and avoid collisions with cars or other vehicles.
In helmets with a transparent face shield, avoid obscuring the field of view by getting paint on the shield. If you spill paint on the face shield, remove it quickly to ensure that it is cleanly and completely removed. Do not intentionally paint designs into the shield, as these obscure your vision and compromise your safety when the helmet is in use.