I have just completed this project. I painted the ceramic tile, sink, and tub. They were all an old "70" pink. I painted them white, and it turned out great. Here's what I did:
1. Cleaned everthing very well
2. Applied a glossy surface primer, purchased at Lowe's
3. Painted the tile with 2 coats of high gloss white paint
4. Painted the sink and tub with a product called "Tough as Tile" it creates a porcelain finish.