Klem,
I always use automotive acrylic to respray die cast models.
It dries very hard, very quickly, and can then be polished using normal automotive polishes and waxes.
I buy spray cans of automotive touch-up paint which have been mixed to manufacturers specs - easy to get the right color.
I've also had specific colors mixed to manufacturers specs (the Poscher 1/6 F-40 and their Testarossa).
I almost never sparay out of the cans - too much orange peel.
It's easier to control the amount of paint you apply by using an airbrush. I use a short length of drinking straw to spray from the can into my airbrush jar. It's very easy to get perfect (or almost) results everytime. Just experiment a little with the correct thinning ratios for whatever paint you're using.
I always spray at around 15-20 psi - and as I get closer to the final topcoat, I use less paint and more thinners - allowing more drying time in between coats.
Liquid paint from a can requires far more thinning than paint from an aerosol spray can.
Cheers,
LeeTree