Scrub the surface to be painted with an ammonia-based household cleaner, soap and water, or a solution of sodium triphosphate. Remove any dirt, grease, chemicals or oil that may be on the plastic item. Any of these impurities can prevent the paint from adhering/bonding to the plastic and will result in peeling paint.
Sand the plastic item lightly, if it had been painted previously. This will remove any flaking or peeling paint, and smooth any imperfections in the surface. It will also create a slightly abraded surface for the paint to adhere to, if the previous finish used was glossy.
Rinse the item with clean water and let dry completely in a protected area. This should take no longer than 12 hours. To hasten the process, dry the item with lint-free towels, then leave in a protected area for two hours.
Move the plastic item into a well-ventilated area. Ensure that the floor is covered with drop cloths or newspaper and masking tape. Move any items that could possibly get hit by over-spray. If the walls closest to the item could be hit by over-spray, take the time to cover them with masking-taped newspaper. Or move your workspace elsewhere.
Shake the spray can for one minute after you hear a rattling sound. Hold the can 8 to 10 inches from the item and slightly to one side. Squeeze the trigger, and move the spray across and off the item. Continue spraying back and forth with slightly overlapping strokes, each time spraying past the edge of the item until the surface is completely covered.
Allow the first coat to dry to the touch. This can take 15 to 20 minutes. Inspect the item to see if there are unevenly coated areas. Apply thin coats of spray until even coverage is achieved.
Allow the item to dry for at least an hour before moving it. Allow to dry and cure for at least seven days to ensure a fully chip-resistant finish.