To manage poor planning effectively in project management, consider implementing the following best practices:

1. **Define Clear Objectives**: Start with a clear understanding of the project goals and objectives. Use SMART criteria (Specific, Measurable, Achievable, Relevant, Time-bound) to define these.
2. **Develop a Detailed Project Plan**: Create a comprehensive project plan that outlines all tasks, deliverables, timelines, and resources required. Use project management software to track progress.
3. **Engage Stakeholders Early**: Involve stakeholders in the planning process to gather their input and ensure their needs and expectations are considered.