Several months ago I created an article with 5 APT (Advanced Packaging Tool) tips for both Debian and Ubuntu available here. APT is the package manager in Debian and Debian-based distributions, like Ubuntu. Here's part two of that article, with 5 more tips and tricks for APT.
This mini-HowTo assumes that you’re running Debian Unstable (Sid), but it should also work if you’re using Testing or even Ubuntu. It also assumes you’re doing all these steps as root.