Sweep then mop the floor. Dirt and dust will interfere with tile adhesion.
Test the floor's paint, if it is painted. If the paint's bond to the floor is weak, it could peel off and take the tile with it. Check the paint's adhesion by placing a strip of duct tape on it. Yank the tape off. If the paint comes off with it, you need to remove all the paint before tiling the floor.
Remove poorly bonded paint using a chemical stripper or solvent. The paint should come right off. If it doesn't, use a floor grinder or soda blaster. You can rent these machines from a hardware store. Once the paint is removed, thoroughly clean the floor again.
Apply adhesive with a trowel. This step is not necessary if you're using peel-and-stick tiles. Residential-grade adhesives come in two main variants, organic mastics and dry-set mortars. Mastics are more vulnerable to high temperatures and water damage. Dry-set mortars are better suited for kitchens and bathrooms.
Wait 30 minutes and test the adhesive by lightly touching it. If it feels moist, wait another 10 minutes and try again. If it's dry to the touch, you're ready to install the tiles.
Push tiles firmly against the cement floor. Once you've installed tiles, wait at least five days before washing them. The tiles should stick for a long time.
Fill the gap between ceramic tiles with grout with a rubber float. Let it dry for 30 minutes, and then clean the edges of tile with a wet sponge. After three hours, wipe away dust.