I use Cosco microfibers with Meguiars All Purpose cleaner at 10:1 if its more than dusty. Once I clean it then I normally use Chemical Guys interior dressing, or one of the Meguiars dressings on a microfiber. Make sure to wipe off excess dressing. Meguiars Natural Shine is cheap and leaves a nice clean 'new' not greasy look to the plastic.
303 protectant is also another good dressing but its harder to find locally. Certain Kragens carry it. It last allot longer than the others I have mentioned but doesn't give as much gloss.