Acrylic paints are a popular choice. Make sure you water down the paints by dipping your brush in some water before you paint on to make each coat as seamless as possible. You will have to do multiple light coats and make sure you let each coat dry completely before continuing.
Seal your paint with varnish once it's done and let them dry until they are no longer tacky. The varnish will ensure that the paint does not chip off, and I find plain acrylic very unpleasant to touch, so the coat helps.