Actually, if you're going to be painting plastic or somethign similar, I would recommend vinyl dye. It actually seeps into the plastic and colors it. This way it won't flake off as easily and it won't make it so your buttons stick and wont' go in the whole way. Easy to use, can get it at any local car parts shop like pep boys. Don't even have to sand at all. You don't need to sand it down at all, but it will show scratches and cracks so you may want to sand those out if you have any. But other than that just spray away and you're ok!

-Sean-