Wash the plastic with warm water and mild dish soap
Rinse thoroughly and dry with a soft microfiber cloth
Remove dirt and grime with a plastic-safe cleaner
Sand scratches with wet/dry sandpaper, starting with a finer grit if possible
Keep the surface wet while sanding
Move to progressively finer grits for a smoother finish
Apply a plastic polish with a microfiber cloth
Buff in small circular motions
Wipe off excess polish with a clean cloth
Repeat polishing until the surface looks clear and smooth
Use a buffing pad or low-speed rotary tool for larger areas
Avoid high heat while polishing
Finish with a clean microfiber cloth
Apply a plastic protectant if needed