One of the causes of the local_settings.py anti-pattern is that putting SECRET_KEY, AWS keys, etc.. values into settings files has problem:
I doing my Django projects using Windows 7 and Powershell, so for me it was slightly different to set the environment variable. Once it was set though, I just did the following in my settings.py file:
import os
SECRET_KEY = os.environ["SOME_SECRET_KEY"]
To set a environment variable in Windows using PowerShell follow the instructions in the link below:
http://technet.microsoft.com/en-us/library/ff730964.aspx