Here's a little walkthrough of my general process in making artwork. This piece in particular was for a Japanese toy monster art show. This character is called Twin Tail. Here's what I did to make my drawing of Twin Tail:
1)I generally start with a sketch on paper. For this one I used some Col-Erase Pencils. I like them because each color has it's own hardness of lead. Also, if I start with one color, I can tighten up a drawing with another color and see where I've been.
2)I scan the sketch or take a photo of it and put it into Adobe Illustrator on it's own layer. In the layers properties, I choose "Dim Images to 50%" for the layer with the sketch. I usually lock this layer, create a new layer on top, and start tracing with the pen tool.
3)Once all the important lines are dropped in, I scale and manipulate the image as needed. Then, I select all the lines and turn them into outlines (Object>Path>Outline Stroke). I then manually nudge all the lines to achieve the thin to thick look that I want. This takes a while to get fast at ;)
4) Behind the line art, on it's own layer, I create areas of flat color. I also knew that for this one I didn't want many black lines, so I made all the lines a color with the intention of changing them later.
5 and 6) At this point it's really about "painting" in the details and highlights on various layers, It's important to keep your layers organized. Merge and label. Oh, and save often.