You'll find that most of us paint everything. A dashboard molded in black would end up getting painted black, then detail painted, but this isn't a hold-fast rule. The trick to detail painting is a good set of brushes, and loading them with paint. You want enough paint on the brush that it flows off and you don't have to brush over the spot twice, and enough but not too much to have good control over the paint application. For things like knobs, buttons and the like, I use a toothpick (and often shape the tip with my knife) dipped in paint, touched on paper to get any excess off, then touched on the knob or button. Detail painting takes patience, and lots of practice. It will get a lot better over time.