Place the tip of your calligraphy pen on your drawing surface to draw thin lines. Use a smooth non-bleeding paper to prevent your marker lines from spreading. Keep the tip pressed against the paper as much as possible while you draw. Lifting and setting it down again can disrupt the flow of the lettering.
Curve your wrist as you move into wider lines. To get these lines with a fine tip, work from the side of the tip rather than the point. Curving your wrist helps you move into a wider line without disrupting the shape of the letter.
Outline your letters to add contrast. A calligraphy pen with a fine tip is ideal for this purpose. To achieve an outline effect, go over the outer perimeter of each letter when it's finished. Apply slightly more pressure to make a more distinct impression in the outline.