Yeah sand it down, you have to use very fine paper just to give it a bit of a coarse surface for something the primer can grab onto. not a lot just a light sand, then prime it, a few coats of pimer very light, follow instructions on can and use PLASTIC PRIMER!! then a few coats of paint, then wait a while like overnight before you laqcuer it, then wait about 2 hours after that before refitting it. Another tip would be that the cigerette lighter is extremely difficult to unplug but dont break it. Also the key to a good finish sounds obvious but dont rush!
The central locking and alarm will be in by 2 tomorrow so i will get the pics of the lockless doors up for you and some of the system. I am lovin it the doors look sweet!!