Although it's tempting to skip this step, you'll have much neater results if you remove the shutters for painting. Vinyl shutters are attached to the siding either with screws or bolts or by mounting clips. Screws and bolts will be apparent on the face of the shutter. If you don't see any, there will be mounting clips behind the shutter. You'll either remove them by lifting up and out or by inserting a screwdriver behind the shutter to release the clip. Label the back of each shutter as you take them off, so they go back to the correct spot.
Take care when removing shutters. Wasps and bats like to nest behind them.
Since most outdoor vinyl shutters are slightly textured, brush marks won't really show as long as you use a good quality paint. Avoid using oil-based paints for shutters, because it's not flexible enough and more prone to fading. Use two coats of a good 100 percent acrylic, or acrylic-urethane blend water-based exterior paint. Shutters can be painted with a brush or a paint sprayer. Alternatively, there are some good canned spray paints that can be used for smooth materials like plastic and vinyl. However, they can be expensive if you have quite a few shutters to paint and have to be applied carefully in several thin coats for a uniform gloss.
Don't use a paint color that's much darker than the original color of your shutters. Dark colors can get quite hot, especially in direct sunlight. This can cause the vinyl to bend and warp.
The best place to paint shutters is out of direct sun and breezes, such as in a garage or basement. Set up saw horses to paint them horizontally. If you're brushing the shutters brush the slatted center first, followed by the outer edges, then finish up with the rest of the front. If spraying, make sure there's plenty of ventilation and cover adjacent surfaces with drop cloths or plastic sheeting. Whichever method you use, do two thin coats instead of one heavy coat of paint.
Let them dry for at least eight hours before replacing them. Keep the paint handy to touch up the fastener heads and any fingerprints after they're replaced.