Article: Take a tape measure, measure out each wall, and then divide the total length of each wall in half. Make a mark at each wall along its center point. Take a chalk line and snap it over the middle of the room to connect two center points across from one another. Then go to the adjacent wall and snap another chalk line across the room. You should have a "+" sign that meets in the center of the room. If you are laying wood flooring, make sure to leave a 12 inch (1.3cm) buffer on all four walls, as the wood needs space to expand and contract. If you install the wood right up against all walls of a room, you'll likely get cracks in the wood when it doesn't have room to expand. If you're laying tile, you don't have to leave any buffer space, as tile does not expand or contract.

What is a summary?
Find the exact center points of all four walls in the room. Connect both pairs of marks on opposite walls with a chalk line. Start laying your wood flooring or tile, using the "+" as your starting point.