ImproperlyConfigured("The SECRET_KEY setting must not be empty.")
This a case of the wrong version of django. Graphite is looking for 1.4. So, use pip to get the right version:
pip install Django==1.4
On Ubuntu 12.10, this got the correct version for me. If not, you may have to use wget to get the correct version from djangoproject.com.
References
https://answers.launchpad.net/graphite/+question/224789
