For line art, Kyle’s Inkbox - Badass Brush at 35 pixels.
For colouring, Kyle’s Inkbox - Roughest Ink No Alias at 40 pixels.
The brush sizes assume a document with a resolution of 300 DPI.
Converting pencil artwork to non-repro blue
Open up the scanned pencil artwork in Photoshop and use a Levels adjustment layer to improve the line quality and whites.
Clean up the artwork with white on a separate layer, if necessary.
Convert the image to grayscale (using the Mode menu found in the Image menu) and then to monotone using 20% cyan as the primary ink. The shade of cyan used might depend on personal preference and printer output.
Cleaning up line art
Clean up the scanned line art in Photoshop with adjustment layers:
Remove any non-repro blue underdrawings with a Hue/Saturation adjustment layer. After choosing the Cyans colour range in the Properties panel, set the saturation to minimimum and lightness to maximum.
Use Curves and/or Levels adjustment layers to improve the line quality and whites, and remove any remaining underdrawings.
For inked line art, use a Threshold adjustment layer to convert the line art to black-and-white bitmap.
At the bottom of the Channels palette, click on Load channel as selection to create a selection of the white areas of the image.
Invert the selection.
Create a fill layer; the selection will be applied to the fill layer’s mask. Alternatively, use the Paint Bucket tool to fill the selection on a new layer.
Deselect the selection.
Delete or hide the scanned artwork and adjustment layers.
Image filesize reduction techniques
Use ExifTool and jpegtran to reduce JPEG image filesizes: jpegtran -optimize -progressive [IMAGE] > [OUTPUT] && exiftool -all= --icc_profile:all [OUTPUT].