Using the Project Plan
The prime purpose of scoping the project is to enable the Project Manager to clarify his or her thinking and to establish what the project will involve, what the risks and possible difficulties are, and how the project should be organised and tackled - and then create a Project Plan that summarises that.
What are the issues? How robust is the plan?
The first task is look at the plan, perhaps with the Project Sponsor and team, and identify the main risks and issues. Can anything now be done to make the plan more robust?
The note "Implementation Planning" under Additional Materials covers some of the most common tactics used to minimise disruption when introducing changes.
Use the Plan to Communicate
Thereafter, it is all about communications. Communicating the project to:
The Project Sponsor,
Meeting with the Project Sponsor to discuss the Project Plan, identify the issues and difficulties, and establish what they can do to help.
The Team
If you have one. By far the best way of achieving this is to involve them in the scoping of the project and creation of the Project Plan. The briefs for the scoping work are designed for this.
Contributors
When the time is right, meeting both with the professional specialist groups such as IT, Communications, etc and people in other sections or directorates whose contribution and cooperation is needed. Using the project plan to clarify what support you need and when you would like it.
Other key stakeholders
Using the plan to simply update them