Hello mate,
I have sprayed various plastics, inside and out on a few Clio's and I had the same worry when I first started. I know on the PH2's (noticed you have a PH1) that the plastics are slightly rough, if that's the same on yours get yourself a selection of sandpapers (halfords sell a pack) ranging from rough grade, to fine. Just sand the s**t out of them, take your time and make sure it's nice and smooth. Even if your plastics are smooth, still give it a sand to ensure your primer bonds well.
Then rub it off with a damp cloth to remove any dust. Get yourself a decent primer, one that's good for use on plastic and give it a couple of coats, again take your time and make sure its completely dry inbetween coats. When your spraying stand back and do long strokes left and right with your hand.....basically don't blitz it with paint as it will run, build it up nice and slowly to give an even covering.
Once all of your primer layers are done and your happy with the covering repeat this but with your colour layer, pearl black in your case (check your paint code for exact black). Once this is dry again repeat this spraying proccess with a lacquer layer, halfords lacquer has always been fine when I've sprayed. When your happy it's best to leave it for a day to completely dry and set to avoid thumb press marks etc when you fit them back on the car.
Sorry for the essay, hope this helps, feel free to PM me if you get stuck.
Mark
