Sand the plastic fairings. It's important to have an appropriate surface for primer and paint to adhere to. Sanding the fairings will create this surface for you. To do this, use 400-grit sand paper. Sand the entire surface of the plastic fairings using circular motions, while applying moderate pressure.
Prime the surface of the fairings. Without primer, the paint will not stick properly to the fairings. This is when chipping and excessive obscurities happen after the final paint job. Apply a plastic primer to the entire surface of the fairings. Plastic primers often come in rattle aerosol containers. It is very easy to apply. Spray long even strokes across the surface, refraining from ever stopping a paint stroke directly on the fairing as to avoid build up. Allow the primer to dry for 2 to 6 hours before moving on.