Audio Post in Audacity for better Screencasts

Screencasting: audio works...

A good screencast is not only about good video, it's also about good audio too. So in post I do not only work on cutting raw footage into something pleasing. I also need to process my raw audio recordings, so they get pleasing too. Luckily, there's a great open source tool for free to do this: Audacity. But what audio processing needs to be done?