PEP 8 (http://www.python.org/dev/peps/pep-0008) provides a style guide for writing Python code. Besides some basic rules, such as indentation, maximum line length, and other details concerning the code layout, PEP 8 also provides a section on naming conventions that most of the code bases follow.
This section provides only a quick summary of PEP 8, and a handy naming guide for each kind of Python syntax element. You should still consider reading the PEP 8 document as mandatory.