You may find the HitchHiker's Guide to Packaging helpful, even though it is incomplete. I'd start with the Quick Start tutorial. Try also just browsing through Python packages on the Python Package Index. Just download the tarball, unpack it, and have a look at the setup.py
file. Or even better, only bother looking through packages that list a public source code repository such as one hosted on GitHub or BitBucket. You're bound to run into one on the front page.
My final suggestion is to just go for it and try making one; don't be afraid to fail. I really didn't understand it until I started making them myself. It's trivial to create a new package on PyPI and just as easy to remove it. So, create a dummy package and play around.