Summarize this article:

Residual dirt can cause your coats of paint to flake or peel. Remove all dirt and grime from your cart with an oil-based dish soap. Hose off the soap with cold water, and dry off your cart with a towel. Avoid applying the paint until your cart is completely dry. Mix dish soap with water in a bucket and apply it to your cart using a rag or sponge. Clean out the inside of your cart as well, removing any belongings or trash, so your cart looks like new once you're finished. Take off any removable parts of the golf cart that you do not want painted. This will prevent them from getting in the way as you work. In addition to the trim, remove the bumpers, roof, and other parts of the frame you don't want to paint. Make a note or take pictures of where each removable piece goes so you know where to reattach them later. For non-removable parts of the golf cart that you want to protect from paint, use masking tape. Keep an eye out for license plates, logos, or other decals that you want to keep visible. Line the outer edges of the windows to keep from spray painting them. Use soft-edged foam tape to avoid damaging your cart. Rub down the area in a circular motion with firm pressure. This will help the paint stick to the golf cart's nonporous surface. Make sure to sand away any old paint to avoid it tinting your fresh coats. Consult a sandpaper size chart to find fine-grit sandpaper. 120 to 400 grits is ideal. After you've finished sanding, use a microfiber cloth to brush off any sanding dust. Primer helps the spray paint adhere smoothly and evenly to the cart. Spray the primer in even amounts over the body of the golf cart and wait approximately twenty minutes before adding on paint. Check the primer's packaging instructions for specifically how long to let it dry. Use a paint primer made specifically for plastic surfaces. If your golf cart is a darker color, apply two coats of primer. Wait twenty to thirty minutes before applying the second coat.

Summary:
Clean your cart. Strip the golf cart of its trim. Apply masking tape to areas you don't want painted. Sand down the body of the cart with fine-grit sandpaper. Apply a thin coat of paint primer to prevent peeling later on.