You need to consider the audience and purpose for your open course/resource.  Who will use it and for what reasons? Do they have specific needs or constraints? These are important questions you will need to think about when creating your open course.  You may have a specific target audience in mind with very particular needs or you might be aiming at a broader range of people who have a general interest in your subject.  You cannot possibly know the context of every potential learner studying your course, however, to help you make the course cover as wide a range of users, needs and motivations for studying as possible, you could draw up personas of specific users to help you plan how to make the activities and content of your course accessible and engaging for everyone.

Write the learning outcomes of your course/resource as you consider audience and purpose. You may find the guide How to write learning outcomes by Bridget Winwood and Alison Purvis will help when writing learning outcomes which are specific, measurable, achievable, relevant and timely.