Whatever channels you may choose (be it search, email, social, mobile), ultimately what users read and interact with is ‘quality content’. Think about this -
At the heart of a good Digital Marketing Strategy lies a cohesive Content Strategy.

Yes, the old adage ‘Content is King’ is perhaps even more important in the Digital age.
How do we go about ensuring the right Content Strategy? Here are 7 key elements to consider -
Engagement objectives – What are your specific objectives to be achieved? These could be brand awareness, lead generation, on site conversions, post purchase loyalty or a combination of the above.
It would be a good practice to consider content creation for each stage of the Customer Decision Journey. Here is an interesting framework developed by BrainRider Marketing group, have a look -

Editorial Strategy - This contains the overall guidelines which defines digital content creation.
It is important to plan for content creation through an editorial calendar, for example having a high level plan on the type of content and the person accountable for this on a weekly basis.
User Generated Content - With the rise of the social web, user generated content, ratings and recommendations play a crucial role to influence prospective customers.

As marketing folks, how can we influence people to share positive reviews and brand mentions about our organisations? This can be done through multiple ways, some of which include setting up polls, asking for user inputs, seeking recommendations for product improvement and running competitions.
Search engine optimization requirements – It is crucial to integrate search marketing principles into content creation. Researching on key topics being discussed on the social web helps provide ideas for content creation.
Consider creating content around ‘long tail’ keywords which are specific to the user buying stage.
For example, if the long tail keywords searched for by prospective customers is ‘buy iphone central london’, then plan for content creation about related topics on this specific long tail keyword. This would ensure higher qualified traffic (users who are considering product purchase) from search engines.
Social sharing – Consider facilitating content creation which users would like to share with friends and peers on the social web. This involves understanding psychology of customers, and the key drivers / motivators as individuals.

It is also important to ensure that social sharing integration is implemented correctly, which further encourages users to share content. Do ensure optimization of various social media platforms as well.
Channel distribution - How do we go about distributing content online?
Set a plan for content distribution which includes identifying the right platforms for different types of content, and establishing a methodology to reach out to key influencers in your audience communities.
Tracking engagement with analytics - Tracking content engagement with web analytics is extremely important. Independent research studies suggests that majority of companies do not check analytics / check and measure the wrong metrics, and hence are not able to take actionable insights.

Keeping track of the right metrics and KPIs would enable incorporating changes to content being developed, to obtain higher efficiency and readership. For example, Econsultancy keeps an active track of user engagement with different blog posts, which in turn helps decide on subsequent blog posts to be produced.
Have any more points to add on? Would love to hear your thoughts.