I’ve got a very extensive guide on how to create good linework in software on my website, which I’ve just updated with some info on Painter’s Liquid Inks. The tutorial is here:
http://www.itchy-animation.co.uk/lines.htm
It covers everything from very slick linework to more rough and scratchy styles. Here’s a pic from the new material - it’s based on a drawing by french comic book artists Andre Franquin, I wanted to emulate the look of indian ink applied with a brush, using Painter’s Liquid Ink technology:

Cheers frog!.. Nice tut mate;) Choc full of inky goodness too!
Thank you for sharing ^^