As mentioned in the video, there are a ton of things you can experiment with when doing line-art, from working on white over black (inverted, working on doing lights) to doing textures and materials. So go crazy and have fun!
Here are some websites and artists that can help you find some inspiration:
Edit: There is now a brush smoothing tool on Photoshop too!
Websites:
Creature box: http://creaturebox.com/gallery/
Inktober Twitter: https://twitter.com/inktober
Artists:
Alphonse Mucha
Sci Scott
David Finch
Aubrey Beardsley