air brush now

It’s my first time using clay (i’m using air-drying clay) and looking for any tips when antiquing the clay, particularly with acrylic paints (or any other cheap methods).

Is it best to start with a dark colour e.g. paint whole of clay sculpture in black, (to fill in any lines/cracks etc), then brush over with a lighter colour when dry? Or paint sculpture in white, then brush over lightly with dark colour?

Any suggestions will be appreciated

Thanks,
Marie