When writing discussions, you'll want to ask yourself a few questions which will help define the types of prompts you'll prepare for your students: What level are my students at in this topic/field? (entry level, mid-level, mastery level, etc.) and At this point in the semester, what is the goal for my students? (foundational knowledge, critical thinking, application, etc.)
Are you ready to breathe new life into your online discussions? [Roles in group discussions] You might want to try out integrating roles into small discussion groups, which can provide more variety in the discussion forum and clearly define tasks. Roles can be assigned to students each week, or you can opt for self-selection using a variety of methods.