Before pulling together an editorial calendar, I created a quick two page doc that clarifies goals, strategies, and metrics for success.
When it comes to content creation, there is really no limit to what can be created. To guide our efforts at Idealist.org, I created a strategy doc which quickly outlined our big goals, strategies, metrics, and tactics. This was a reference document that influenced the editorial calendar and data analysis.
One thing I strive to include are internal goals. Improvement of processes, professional development for staff, growth of freelancer network, and other operational goals are critical for content strategy success.