Best practices to manage inaccurate estimates in project management include:

1. **Use Historical Data**: Leverage data from past projects to make more accurate estimations. Analyze previous costs and timelines for similar tasks.
2. **Involve Experts**: Engage team members or subject matter experts who have experience in similar projects to provide insights into cost factors.
3. **Break Down Tasks**: Decompose larger tasks into smaller, more manageable components. This detailed approach can help in providing more accurate estimates.