I dont feel confident offering anything that might be misconstrued as definitive, but I know a lot of aspiring artists would love some general pointers, and I think I've put in enough hard time to share the few I've gleaned.
A well inked piece can stand alone without color or shading. Do you know why? Because the artist has determined the light source ahead of time, and utilizes this knowledge while inking. Your heavier lineweights will be away from the light, your lighter ones will be closer. In real life, there are no harsh lines, merely cast shadows. When we draw lineart, we are using lines to delineate one object or layer from another. Objects closer to the viewer will generally have a heavier lineweight than those farther away.
|Even in very open inks such as these, I've still cast some shadows in black. Where cloth overlaps cloth, cloth overlaps skin, the bottom of boots, or skin overlaps skin, or hair overlaps skin there is some cast shadow. Basically overlap=cast shadow.|
|Red circles denote areas of overlap where the lineart has gone thicker.|
|I've found that by adding some cast shadow to the inks, one can convey the thickness of clothing much more effectively.|
With exception, lighter weighted objects (feathers, hair) will have a lighter lineweight than heavier objects (anvils, whales), because the lineweight gives the audience some idea as to the nature of the object. Lighter colored objects (wool, clouds) will have fewer surface details than darker colored objects (coal, tree bark), because every line you add contributes to an overall greytone affect on the piece when viewed from a distance. Objects that warrant the reader's interest will usually have either more details than the surrounding area or fewer, creating contrast and attracting attention.
|The couple and the treehouse both have more overall details than the background woods, attracting attention.|
Variation in lineweight is important, as it keeps your piece from becoming flat. Flat and designy doesn't have to be a BAD thing, but you want your work to feel flat and designy by choice, not because you were too lazy to utilize lineweight. Even within a single face, there should be variation in lineweight.
My mentor years ago suggested I do all my art digitally because there is an infinite amount of digital paper. This is true, but you should work in the medium that A: you feel comfortable with and B: accomplishes the goals you set out to accomplish. Don't waste time trying to recreate watercolor digitally if you know how to use watercolors and own them. Choose the media that accomplishes your goals elegantly. Tech pens travel well. Nibs are expressive. Brushes can be fast. Digital allows for infinite correction. Don't try to force one tool to suffice for many.
|Brushpen, no pencil layer, done in maybe five minutes.|
|Digital ink. Specified by commissioner, about 20 hours, tone was applied digitally. Inked for B+W.|
|Brushpen, 2-3 hours|
|Tech pens, brush to fill in|
Inking with color in mind is very different from inking a high contrast, black and white image. When you are working in two colors (black, white), you should be more generous with your spotblacks, cast shadows, and surface details. When inking for color, too many spot blacks will look awkward with a colored piece, so dial it back a bit, unless you want to look like Mike Mignola (I love Hellboy, so this is in no way meant to be derogatory).
|Inked for black and white. Notice- a lot more spot blacks and surface details.|
Dont rely on crosshatching or tone, they'll flatten your image. Use contour lines and patterns that follow the surface of the object they're on.