Clean and level the floor upon which you are going to lay the tile. Plane flat any floorboards that stick up.
Find the exact center of the room. Measure and mark the central point on each wall, and then use a chalk line to mark a cross through the middle of the room, from each point to the one directly opposite it.
If your tiles are not self-sticking, apply a coat of adhesive to one quarter of the floor, following the directions provided on the package. After waiting the specified amount of time for the adhesive to become tacky, begin laying the first row of tiles, starting at the center of the floor.
Lay each tile straight downward, without sliding. Make sure the tiles are pressed tightly against each other. When you come to the edge of the wall, you will likely find that there will be a gap into which a tile will not fit. You will have to cut a tile to fit the gap. one way to measure for this is to lay a tile directly on top of the last tile laid, and then butt a tile against the wall, laying it on top of the first tile. Mark the first tile where the edge of the second crosses it, and cut with a tile-cutter. Lay the half-tile in the gap, making a complete line from the center of the room to the wall.
Lay the first tile of the second row half a tile's width closer to the wall than the very first tile laid. Continue laying the row all the way to wall. Start the third row on a level with the first tile, and alternate the placement of the rows for the rest of the room's quarter, creating a brick pattern.
Repeat the steps for the other three quarters. Note that the staggered rows of both quarters in the half of the room which meets the first quarter end-on will have to be begun half a tile's width out, rather than half a width in, so as to not leave any gaps.