Floor tiles have traditionally been laid in rows that all line up on the floor. However, they don't have to be installed that way. You can stagger or even set them up in a diamond pattern. Staggering the tiles isn't any more work than the traditional rows but can give you a whole new look. You can even purchase tile now that looks like wood and works great with a staggered installation.
Use a laser level to give you a straight line across the longest unobstructed wall. Snap a chalk line along the level mark. Most walls are not straight all the way across. This is why you use a level. The gap will be covered with grout or baseboard.
Trowel on the thin set mortar mix to lay down the tile. Work in sections that you can reach, or do one complete row and come back to do the next.
Lay down the first row of tiles using spacers between each tile. Spacers come in many sizes, so choose the size that looks good with your type of tile.
Start your second row with a half tile. Measure and cut the tile in half using a wet saw. Measure on each side and then draw a line across with a straight edge. If you don't have a wet saw, you can rent one at the local tool rental store.
Put down more thin set and set the half tile, then continue with full tiles and the tile will be staggered. When you start the third row, use a full tile. Continue back and forth with a half tile and then full tile until the room is completely tiled.