Usually, it is possible to apply paint to glazed ceramic tiles if they are on a wall in a dry room. However, it is important to remove any trace of grease and dirt that may be trapped in the joints of the tiles.  Prepare the surface using paint wash, and dull the surface using fine-grade wet-and-dry sanding paper. Prime the surface using Colorex Häftprimer Aqua adhesion primer, and then apply two coats of Colorex Briljant Lacquer Paint in the colour of your choice.