Applying paint to ceramic tiles is usually a short-term solution because, no matter how careful you are with preparation and application, paint will eventually chip or peel away from the glazed surface.
However, if you have a run of ugly tiles, giving them a quick coat of paint can act as a good facelift. Prepare the tiles for painting by washing them down with household detergent and a damp cloth.
It is now possible to purchase a proprietary tile primer which may prolong the life of a coat of paint. After this primer you should use two coats of gloss or enamel paint if you want a durable, waterproof fmish.