Try automotive paints. I used to use automotive acrylics, aplied directly to the plastic (airbrush only). The adherence of the paint is very strong and it don't need any primer, and you can put any masking tape over the paint - it don't peel or mar! You can handle the kit without any fear. The fast drying time (approx. 15~30 minutes) is another good feature of this paint. And yet, if you want, you can polish the painting (just like a "real" car painting).
The "aluminun" automotive acrylics provides an absolutely real metal finish, for me it is the ultimate metal finishing for plastic models.