How to paint a spherical object

I would balance the ball on an empty can or something similar. Paint all the areas that are exposed but use a light touch on the paint to start. Let that dry completely then turn the ball so that the unpainted piece is exposed. Then continue painting. The key will be patience waiting for the paint to dry thoroughly and light coats so no drips can develop.

Spray paint. Several light coats.

use paper and tape to cover where you do not want paint

I would use a sponge brush and almost dry brush the paint on slowly. Agree with the commenter above that you'll have to have patience between coats.

On easy way to put them on top of a length of styrofoam and slowly pour paint over the ball letting it drop off the excess into the styrofoam. It covers well and doesn't use up a lot of paint