Once you're satisfied with the look of your pattern, you can paint a darker shade of paint over the whole ball.
We decided that black was to dark and sharp as a contrast, so we mixed a darker grey colour. The paint is a mix of acrylic paint and a chalk paint, to give it a not so glossy finish. We found this paint in the hardware store.
Paint the ball completely or work in segments - it all depends on your taste. We peeled the masking tape not long after painting. Make sure to press the tape very well down before you paint, avoiding blotches and noses doing so. But even if you have some slight uneven lines - the end result will be great, because the Death star has so many little bits and dots, it will look like you wanted it this way ;)
The round weapon was painted by hand with a fine brush.