Other's may differ on this, but I wouldn't recomened trying to paint ceramic tile on a floor. It can be done to tile that is on the wall, but floors are walked on and wear too easily.
Just in case, here is the procedure to paint ceramic tile on walls. Check with a quality paint supply store, make sure the person you talk to has some expirence, the process is not easy and maybe impossible to reverse.
To paint CERAMIC WALL tile, first wash thoroghly with a strong cleaner and allow to dry for at least one day. When it's fully dry use a fine grit sandpaper to degloss the surface. it is really important to be certain that the surface is completly sanded and deglossed. Clean the dust off with a damp sponge and allow to dry again overnight.
The only way to get paint to stick to a surface as hard as ceramic is to use XIM primer. This stuff is not widely known and has unique properties. XIM is an adhesion primer that sticks like no other primer I have ever used. There is, to my knowledge, no other primer that will stick to this surface, so don't buy anything but XIM. The clear XIM is easier to brush and roll than the White tinted one, but the clear may not be suitable for this. The clear one dries really hard and some paints won't adhere to it without a thorough sanding with fine sandpaper.
Here is the fly in the soup; epoxy paints may not be compatible (I'm almost certain that they aren't) with XIM. Most paints and primers will lift when an epoxy is applied over them. A floor enamel would be better. Here is another fly, XIM may not be suitable as a primer for a surface that is going to be walked on.
Get advice from others before you try this. As I said, this process may be irreversable, and replacing your tile isn't cheap.