So I thought I'd post some tips on techniques and materials–mostly so I don't forget what I've learned through the school of trial and error.
Tip #1: You don't have to get the most expensive brushes to pull off excellent inking art. I've owned Windsor Newton brushes in the past (and they are wonderful brushes), but you can avoid the sticker shock of the Series 7 brushes by trying lesser-known brands for your cartoon inking. Princeton's
9560 Snap! series is one example. I use their Round #6 and even though it’s a synthetic brush, it loads ink well and handles beautifully, yielding wonderful thick and think lines.
Tip #2: One big issue in using synthetic brushes successfully is keeping tips intact. I've experimented with home remedies and found that CVS styling gel (which is water soluble and contains glycerin) does a great job in keeping your brush tip in shape. I just wash my brush immediately after each use, then apply a generous glob of gel, making sure to work it into the brush fibers. Then I sculpt the brush tip in the fold between my thumb and index finger. Works like a charm. When I next use the brush, I rinse if off easily with water and I'm ready to go!