With flexible pointed or ball pointed nibs you can create different stroke widths by applying pressure to the nib as the nib is pulled. Sideway or upwart strokes remain thin. If you apply pressure here, the nib may get stuck in the paper or scratch.
In this short Video you can see how it works.
With flexible pointed nibs the stroke sequence is the same as with the round hand lettering nibs.
Get familiar to the technique by drawing squiggles and ornaments.