I would recommend looking at "Expert Python Programming: Best
practices for designing, coding, and distributing your Python
software".
The publisher's page is here:
http://www.packtpub.com/expert-python-programming/book
...and a sample chapter is here:
http://www.packtpub.com/files/expert-python-programming-sample-chapter-chapter-10-documenting-your-project.pdf
I haven't read it myself *yet*, but the reviews I've seen have put it
very next in line in my reading list. According to the majority of
those reviews, the book is far from perfect - lots of editing errors,
as the author's native tongue is not English - but as a whole, it's
valuable enough for what it does to be more than worthwhile.
Also, if you find some good suggestions elsewhere, report it back to
the list! I'd love to hear more about additional "best practices"
Python books!
Good luck,
Jens