One of the ways that you can add value as a project manager is to bring clarity to projects, especially project decisions. How do you do that?
1. Keep a list of unanswered questions. Prioritize them and go about finding answers.
2. Create a framework of unknowns such as budgets, timeframes, people, approvals; use forms, templates, and spreadsheets.
3. Build a straw plan for people to attack by inserting draft or estimated values in your framework of unknowns.
Over time a clearer picture of the project plan emerges as people attack, question, and answer the straw values in the plan.
This framework of unknowns is like the scaffolding that is used to build a building. As the project progresses, you have a clearer blueprint and can slowly dismantle the scaffolding.