4-3 Graph Paper
Graph paper is very helpful when preparing freehand sketches. It helps you to sketch straight lines, allows you to set up guide points for curved lines, and can be used to establish proportions. It is recommended that you start by doing all two-dimensional sketches on graph paper. As your sketching becomes more proficient, you may sketch on plain paper, but because most technical sketching requires some attention to correct proportions, grid paper will always be helpful.
Graph paper is available in many different scales and in both inch and metric units. Some graph paper is printed with light-blue lines, since many copying machines cannot easily reproduce blue lines. This means that copies of the sketches done on light-blue guidelines will appear to have been drawn on plain paper and will include only the sketch.