I'm experimenting now with Faber-Castell colored ink pens. Colored pencil was not producing the hard lines and consistently saturated fills essential to cartooning. Killer Klowns seemed, for some reason, like a good subject. Here's my first attempt.
Colored ink demands a new technique. The first difficulty I encountered was keeping the inks from bleeding into one another at the edges. How to overcome this? First, be very careful. Second, clean the tip on a paper towel when a different color ink bleeds onto a pen tip.
Producing consistently and fully saturated fills is something I don't know how to do yet. I'm doing better, but I haven't yet grasped a technique to really works.