Instructions
Clarity on what participants are expected to do
If participants are unclear on what to do, they will wait rather than ask, and silence online reads as compliance, not confusion.
Clear instructions are important in any workshop, but online the stakes are higher. In a physical room someone will catch a confused neighbour and explain quietly, or a visible look of puzzlement prompts you to clarify. Online, confusion is invisible. People sit with it, do the wrong thing, or disengage.
Good online instructions are shorter than you think they need to be, concrete about what participants actually do (not just what they will get out of it), and repeated in at least two places: spoken and visible on screen or in a shared document. When in doubt, add a worked example.