Before you can set the first tile you need to take a look at where you are going to put them. What do you have in place already? Is it wood, masonry, linoleum or old tile. Often it will be necessary to remove the old before you can install the new. If the old covering is solid and in good condition you can usually tile right over it - even if the old covering is tile!
Ceramic tile requires a solid base, or underlayment, to sit on. Tile is heavy and of course must support the additional weight of foot traffic on a floor or pots, pans and whatever on a counter. If the old covering is in bad condition or unreliable for any reason do yourself a favor and get rid of it.
The underlayment must be clean, flat and stable. When removing old covering be sure that you don't leave any bumps, holes or debris. Also, be sure to vacuum up the dust left by the removal. Tile is strong but brittle, it is easily chipped and cracked. That is why the underlayment must be flat and stable. If dust gets in the adhesive it will cause it to lose it's stickyness and the new tiles will become loose.
The best underlayments for ceramic tile are backer board, plywood, drywall, mortar bed and old ceramic or vinyl flooring. Backer board is board especially designed for ceramic tile. You can't go wrong with it. A mortar bed is a concrete slab - don't fool with that if you are not an expert. If you plan to set the tile yourself you may want to hire a contractor to lay the mortar.
If you plan to have the tile set by someone else be sure to figure the cost of removing old covering and readying the underlayment into your estimates. As you can see from the above it can make a considerable difference to the final cost of the project. Ceramic tile is great but if the cost is prohibitive switch to something more reasonable.
