I did for mine;
Soaked the parts in boiling hot water with washing up liquid in for about 10 minutes to get rid of any dirt and waxy coating
Dried completeley with a tea towel
Wet and dry paper, can't remember the number to be honest maybe 800/80 until smooth
One coat of primer, let to dry for 15 mins, then added another coat.
Once left to dry for 30 mins, I put my first coat of paint on, left to dry for about 20 mins, then repeated the process 3 times
You can add a coat of lquer(sp) to make it last if you want but I never
BUT don't try to put them on the same day even if the paint is dry when you touch it as your fingerprint will still be inprinted into the pain when trying to push the parts abck into place, I found this the hard way