Best of luck with the project.
I've painted 2 cases using a black lacquer finish and they came out much better than I thought they would. It was pretty simple too.
just a couple of suggestions -
Use steel wool to "clean" the case thoroughly, then blow it out with compressed air and wipe down.
Grab a can of adhesion promoter.
Wet sand between coats using soapy water for a very even, clean surface.
Post some pics of the finished project.