Notice 2 different pen sizes used (.5, .7). Also study the use of cross-hatching to create form and contrast.
This is how one learns to make consistent lines. Fill a page! Extra credit to those who take it on! (Ok, extra cookie perhaps)
Edward Gorey technique inspired.
More playing with line (and pen sizes).
And another page of line play! Some days you just have to explore the pen and how you use it.