Seek capable, motivated owners for each lowest-level activity. Staff all work possible using willing volunteers, and remember that the project leader remains responsible for all tasks without an owner.
For each activity, assign one and only one owner, delegating responsibility for the work. Owners will be responsible for planning, estimating, monitoring, and reporting on the activity, but will not necessarily do all the work alone. In some cases, owners will lead a team doing the work, or even serve as liaisons for outsourced tasks. For each activity, identify all needed skills, staff, and any other resources.