Research tile and find out what type and size fits your needs. Tile must be installed on at least one and a half inch of sub floor ; or you can use a concrete backer board.(thinset backer board to floor and screw off or roofing nail it). Measure square footage and purchase an extra box for mistakes.
Check for square walls and measure off of two square walls and find center of room. Measure that distance from one end and then the other. Repeat off other square wall and strike lines, take the distance and divide it into size of your tile to find out how the tile will end up from wall to wall; and include size of grout lines. Start either with the tile on the edge of your lines or place the tile in the middle; that way all of your tiles will come out the same all the way around the room. Mix a bucket of thinset and trowel out some thinset with quarter inch notch trowel. Place in tiles gently in a turning motion, back and forth while staying in the lines. Use appropriate spacers.
Do not tile yourself into a corner. After placing all of your full uncut tiles measure out edge tiles and cut to size. If you have a door way or transition between rooms you can use a slueter strip that you thinset in with the tile or a transition strip over the top. You can back butter the smaller pieces if needed. Finish placing cut tiles. Stay off of tile over night; 24 hours to let thinset cure. Mix grout and float into lines with grout float.
Float grout at a 45 degree angle making sure all areas are completely stuffed with grout. Let stand until a haze appears. Carefully wipe tiles with clean sponge and water. Tiles will again get a haze, repeat; changing water often. Make sure you don’t pull grout out or get too wet. Let dry over night, and seal tile and / or grout as directed by manufacturers. Enjoy your beautiful new floor.