At the request of certain people, these are a set of tutorials/lectures posted or linked to by me, Esrix. However, there is no one definite be-all-and-end-all method of doing this kind of stuff. I encourage you to read as many tutorials as you can and use the methods that work best for you..

PLEASE READ THIS FIRST!!!
-Updated 07/03/2007-
Please read this before beginning any of the tutorials.
This holds general information about hardware, software, disclaimers, and how to properly prepare to do your art.

Basic coloring tutorial
- Updated 08/23/2004-
How to apply basic color to your images

What are masks?-
-Updated 03/26/2006-
What you can do when you apply masks to layers

Shading and highlights using Masks
-Updated 12/1/2005-
Adding value and depth in a few easy layers using masks

My thoughts on Drawing
-Updated 5/31/2005-
Not a tutorial, but rather some thoughts on how to improve drawing skills.

A Slightly More Cost Efficient Way to Make Your Own Comics
-Updated 12/2/2005-
A tutorial that uses unconventional means to make comics more efficiently using computer technology

Tutorials by the great H.S. Kim of Kung Fool fame
This is a great set of tutorials coming from another web cartoonist. Hyung Sun Kim shows how he goes about the process of making a comic, covering everything from thumbnailing to penciling to inking to scanning and even Photoshop touch-ups. Definitely something to add to your bookmarks.