Use a ruler and be precise about measurement and the straightness of your lines. Take your time. Draw lightly to start and darken your lines when you have them correct.
Assignment: Use an “H” pencil. Create a 7″ square in the center of a page in your sketchbook. Divide the page into nine sections with at least a 1/2″ even border between all nine squares. Create an “x” from corner to corner. Connect the corners of the square to the vanishing point found in the middle (where the “X” lines meet). Draw lines for shading, dark areas. Erase all unusable lines. Using “4B” or “Ebony” pencil go over the necessary lines to re create nine squares in one point perspective.