Clean the shutters. Use the garden hose at full force to blast off spider webs and grime. If the shutters are secured with screws, the shutters can be removed to clean and paint. If leaving the shutters attached to the house during the painting process and there are plantings beneath the window, wet the soil around the plants to help dilute any paint or cleaning products that drip. Covering the plantings with a canvas or plastic tarp can further protect them. When finished, wet the soil again to further dilute any dripped products.
Mix warm water, about two tablespoons of a grime-cutting dish detergent, and about 1/2 to 1 cup chlorine bleach in a bucket of water. An "oxygen" bleach product can be substituted for chlorine bleach. Bleach helps to remove mildew; if no mildew is present, eliminate the bleach.
Wearing rubber gloves, use a scrub brush to thoroughly clean the shutters. Rinse immediately and allow to air dry.
Sand the shutters to rough up the surface for better primer adhesion. Use a fine, 150- to 180-grit sandpaper.
Apply an exterior latex urethane primer according to the manufacturer's instruction. Primer prepares the surface for painting. Latex urethane primer is best suited to adapt to the expanding and contracting nature of vinyl. If applying spray primer, tape newspaper to the surrounding surfaces for protection. If possible, prime and paint the shutters on an overcast day so the vinyl will not be hot from the sun.
Apply latex urethane paint according to the manufacturer's instructions after the priming has thoroughly dried. Two or more coats of paint may be needed. Allow the paint to dry between coats.
Reinstall the shutters or remove newspaper protecting the walls.