Drawing with pen is different than working with other drawing media:
- no tonal variation of the drawing tip (unlike a graphite pencil).
- pressure, that you apply while drawing, DOES matter - lines change thickness as you press harder (unlike a fine-tip marker).
So, to create value and texture variations - you need to use different strokes, patterns, alter space between stokes, change stroke length and thickness, overlap strokes, etc. This is why we are going to start with a series of exercises.