The problem with painting ceramic tile is getting the bite the paint wants to hold well. There are some special paints to use but most epoxy based (two part paints) will etch pretty well. try scuffing the tile first with sand paper some types of ceramic scuff better then others.; Beware it this is floor tile the paint may be short lived in a wear area. I have seen the bath tub epoxy based resurfacing paints used will good results on wall tile.