I noticed a slight deficiency around here in terms of new art, so I thought I’d peel some skin back and show some bones for a little bit. Closetworld is a webcomic written by Matt Yocum that went online a little while back. As pretty standard procedure for all my projects, I make sure thumbnails are approved by the writer and/or editor before I actually begin work on the page. Below are the layouts for the first four pages of Closetworld, and the finished sequentials for comparison. As usual, click to biggify.
Aside from camera placement and shot angle, two other very good uses of thumbnails are the preconception of Shadow Placement and Shorthand of Expression. Figuring out where your shadows go in this miniature version of the page saves you a lot of time and ink. It’s not just shadows really, but blacks in general. If the page reads smoothly as a small sketch, there’s no reason for the finished version to be weak compositionally.
As for shorthanding expression — it can get tedious when you’re already drawing the page and you need to keep checking the script to see if the emotion on your character’s face fits what he’s saying and doing. If you indicate this in your thumbnails ahead of time, you save yourself quite a bit of hassle later on.