A lot of the time the size of the image you want to reproduce will be different to the size you want. The method explained here to convert the image to the desired size is the grid system.
You will need to buy or draw up a grid on tracing paper and place it over the original image. Draw the image outlineonto the paper. Then using your tracing as a guide reduce or enlarge the image onto another sheet of grid paper. When reducing use a small scale grid,enlarging, a larger grid. To transfer a key point, firstly determine where it lies on the grid by counting down and across. Then reverse the procedure to plot the point on the second grid. After plotting all of the key points, draw in the details.
Pencils
Use a 2B for drawing and tracing designs.
5H for transferring the designs on to projects.