I've got a line art drawing of a dragon that I'm trying to color. I don't necessarily care if I use Illustrator, Photoshop, or Sketchbook Pro; I'm just trying to figure out the best way to color the drawing. I created the line art image in Illustrator.
I know to use live paint and live paint bucket for contained lines, but how do I easily 'fill' in areas, like the fur on the chest, that isn't a fillable object? I know how to do it the painful way, i.e. duplicate the lines, complete them to create a closed container, and then fill that container...but ugh, takes forever.
So probably the coloring I'm looking for is 'cel shading' style:
Also, the line art was done in two stages. In the first step I used (accidentally) a calligraphy brush that, when I turned on live paint, dumped out to simple line art. I then had to do a bunch of touch-ups, and those were done with a line art brush, so they're thicker. Hence the 'poor' quality. I'm certainly open to suggestions--I'm new to the digital illustration world. I've got a ton of experience with PS/AI, just not in this particular space!
This is a bit broad, not knowing the style of coloring you are after.
If you merely want flat solid colors, then Illustrator's Live Paint Bucket Tool will handle that just fine. Select all, grab the Live Paint Bucket Tool and start clicking.
If you want more painterly color (and it sounds like you do) then Illustrator isn't a good tool for that. I would copy the line art and paste it as a Smart Object into Photoshop. Set the Smart Object blend mode to Multiply. Then add layers below the smart object and paint colors on those layers with a brush.
Illustrator is for flat solid shapes or gradients. If you want smooth transitions between areas, you'll need to create additional shapes and apply either gradients or gradient meshes to those shapes. You can not easily get color transitions with Illustrator unless you manually create additional shapes.
To complete the cell style of color you'll need to think of the piece in terms of shapes for each color area, not as a whole. Live Paint isn't going to work, but it's possible in Illustrator.
Basically you need to think like you were working with cut out pieces of construction paper for each color - manually creating shapes for highlights and variations.
Here's a quick example of an object stack to color the tail:
The best thing you can do to facilitate this type of coloring is to learn to close your paths and create shapes, rather than a series of disconnected paths. Vector coloring works much better and is far more reliable when shape with fills are closed. Live Paint will auto-close many things, if Live Paint is an option but for many things Live Paint simply isn't appropriate. You can start with the Live Paint Bucket Tool to A) Close Shapes, and B) lay base tones down. But after that you need to grab the Pen Tool or something to create additional shapes for additional color areas.