Then, with a black felt-tip pen, trace around the pencil markings, making the lines thick so that they stand out. At this point you will also want to color in any of the areas on the cutout that you want to remain black in the finished product (e.g. shadow of clothing, etc.).

When you begin cutting (in the next step), you need to cut along both sides of the thick lines that you’ve just created with the black marker.
You don’t want to make any mistakes here, so it’s safest if you make a few copies of the sketch as back-ups, just in case.