Design Tricks with the Pencil and Brush
The Pencil tool can be used in its own unique way in conjunction with the Inkbottle tool. The inkbottle will draw a line around the contour of any painted object. Look at the following figure examples. First select the inkbottle and make sure you have the hairline stroke selected. Then tap the inside of the filled shape, in this case the white eyefill. This creates an outline around the eyefill contour. Select your new pencil line and, using your arrow keys, move it a few pixels over. Now select your paint bucket and fill in the space you have created with a new color. To create this kind of effect, you always want to use a color slightly lighter or darker than the color next to it. When using this technique be sure you have your selected close large gaps in the gap options, otherwise your spaces will not always fill with colors when you dump paint in them.
By now you should know that if you paint a stroke over a previously painted stroke on the same layer, the new stroke will cover (or eat away) the old stroke. This can be used to your advantage. I often design my keyframes in one color and then refine the pose directly on top of the old one in another color. When I am done I simply remove the first pose by selecting its color. The paintbrush can also be used as a great cleanup tool. The following figure was trace bitmapped and left me with thousands of jagged edges. These jagged edges could end up creating a large file size. By simply tracing over the outermost part of the artwork with my red paintbrush, I have deleted the jagged edges. Simply remove the red paint stroke after you have finished tracing the object and you're done.
The Paintbrush and Pencil tools also offer the artist an array of shapes and strokes. Besides giving you various brush sizes, the Paintbrush tool also offers you a multitude of shaped brushes to vary your line quality. Experiment with these features to create new styles and designs.