I typically zoom in to 100-150% in photoshop.
My files are usually 300-350dpi, so @ 100% they're usually quite large.
I use a hard-round paintbrush in photoshop. They're usually the first 5 brushes you'll find in photoshop by default. It's set to taper with pen pressure.
@350 dpi I usually work with a 5 pixel tapered paintbrush to get the line thickness you see in my work. I've seen artists work with thinner lines and thicker lines than this.
For really long, perfectly curved lines I'll typically use the pen tool to create a path that I then stroke. Getting a long, completely smooth line is very difficult freehand.
If you're curious, you can watch one of the inking streams from my livestream video library here: http://neondragonart.com/stream.html
Hope that helps!
If you visit www.nn4b.com
, my roommate Alex does his linework a different way. he works at 350 dpi and uses the pencil tool to do his lines. There's no taper to it and it creates hard, pixelated, aliased lines. When you view the images at 72 dpi, they linework appears crisp, thin, and smooth. Because he works with the pencil tool, he can easily paint bucket fill his linework, which speeds up his process. His line art in general looks a lot thinner than mine.