Sweep the floor to remove all dust and loose debris.
Mop the floor with hot, soapy water to remove all grime and caked soil. Then allow it to dry thoroughly.
Scrap up any stubborn debris or wax with a razor blade.
Look for any cracks or uneven spots in the floor. If you find any, select a floor-filling compound that is designed for the surface you are covering. Floor-filling compound is used to level surfaces and fill depressions. Mix the compound according to the manufacturer's instructions.
Spread the filling compound into the cracks and uneven dips in the floor with a trowel. Smooth the compound into the cracks until the floor is even. Allow it to dry for at least an hour. The floor is now ready for tiling.