Inking is pretty much tracing your pencils. And the tool that works for this task the best is the Pen Tool .

This is essentially a vector tool. If you've ever handled programs like Corel Draw!, Adobe Illustrator or Macromedia's Freehand, then you're familiar with what this tool can do.

The above image you can see the pen's options. I've indicated the settings you'll want to select for the specific task of inking.

Using the pen tool means you're going to be working with paths. Paths are lines that you can control the shape and size of. Anchor nodes are used to place specific points, while the direction points are used to curve a path. Practical use for this tool alongside with the Brush Tool can be seen in the inking tutorial.