You might have already seen this example in the Community section, but I thought I'd post it here too. This is hatching practice with a few different pens and a pencil, illustrating six layers to a single layer each. Also, dots (stippling) added to a patch to show a mixed tonal effect.
One thing I'd change on these gradients would be to have them end with the two hatch section as both 45 degree marks, rather than one 45 and one horizontal. But this is why I practice. ;)
Update for 5 August, 2016: Here's a sketch I added to a community post for this class, but thought you might like to see it in my project workspace. It's a sketch I made of a cloud-filled landscape using watercolour, plus white and black ink. Notice the hatching is done in white, grey, and black.
I tend to do a lot of hatching and pen and ink work when I'm having focus issues - it just brings my brain back to earth, if that makes sense.
Here are a couple works in progress. The first is watercolour with white acrylic ink and hatching marks only a couple millimetres long each.
I make lots of these pebble style pieces which are inspired by my local beach (also in progress):
And this is where the practice helps out in a typical illustration, this one, part of a larger piece for a book I'm writing (the marks were so much easier after all the pen practice):
Looking forward to seeing your ink work, both the practice and how you tie it into your art style!