Door Panel Questions

[GOPAPA]

I am wanting to paint my door panels a semi-gloss black .

I washed the panels with a SOS pad and now would appreciate some info on what is the best way to make sure the paint sticks and does not peel off after I paint them.

Pictures show that I have went through the black that is on them with the SOS pads in some places and other places I have not.

I plan on shining up the chrome and putting it back on the panels with out the metal woodgrain insert ..

The places that I have gone through the paint is showing what the plastic looks like from the rear side of the panels ..

My questions are these ..Do I have to take off all the black on the panels ? Or do I only need to get off the paint that comes off by scrubbing them like that is shown in my pictures below .. Do I need a primer first before I paint the simi-gloss black ?

Was hoping that some others have been there done this and know whats best ..thanks GP Larry