I've just written this article for Motional.net on improving performance when working in After Effects. Some of the features covered are fairly basic, but it's always good to know the little tricks you can do to speed things up.
After Effects timesaving: Rendering | Motional
An article I wrote quite some time ago has been proving popular, so I thought I'd post it here too. Its gives some basic tips for saving time on your After Effects Renders, along with some more advanced ones. I've already posted a shortcuts article, I'm going to start putting together a general workflow one next.