A collection of links to twenty great comics and cartooning tutorials over at PSDtuts. Lots of tips for inking in both Photoshop and Illustrator, coloring, using Photoshop layers to your advantage, achieving halftone effects and other comic-book style looks to your art.
A great resource. You can never have too much information about how other artists use graphics software to create their work. I often take tips from multiple tutorials and create my own workflow from just a tip here and a technique there.
Sometimes (and probably most of the time) merely seeing how an effect is achieved will offer no clues as to what it’s like to create that effect for yourself. Copying or mimicking the effect can help, but those moments where it works within your own artwork should be explored the moment they happen.