According to home improvement expert Bob Vila, all tile flooring must be laid on a solid floor to prevent cracking. Although this may seem counterintuitive for a vinyl product, the concern is for the grout -- it too will eventually develop cracks if not laid on a level, solid subfloor. Take up the existing flooring if there is any. You'll need a tape measure, pencil, chalk line, metal ruler, sharp utility knife, tile spacers, grout, water, a bucket and a rubber grout float.
Mark intersecting chalk lines at the center of the room and start there. Lay out your tile squares with tile spacers in between to ensure even and uniform grout lines. Use your utility knife and ruler to cut out the tiles around the edges to fit. Once you've laid out the tiles to your satisfaction, peel the paper backing off of the tiles and stick them to the subfloor one by one until all the tile has been laid. Remove the tile spacers before moving on to the grout.
Mix your grout product with water to a peanut butter consistency, or according to the manufacturer's instructions. Place a blob of grout on the floor to work with and use your grout float to pack the grout into the spaces between each tile. Use a squeegee motion with the float held at an angle to fill the lines. Work in small areas until you've covered the entire floor. Use a clean float to remove excess grout from the floor. Let the grout set for about 15 minutes and then wipe the floor clean of grout residue with a damp sponge. Keep a bucket of clean water handy to rinse out the sponge frequently. Let the grout dry completely for 24 hours or as directed on the product label.
Make sure the room you're working in has been at room temperature for at least 48 hours before you begin working.
To remove any leftover grout haze after the grout is completely dry, wash the floor thoroughly with 1 cup of white vinegar diluted in 1 gallon of water.