To develop an internal audit plan that aligns with ISO 9001 standards, focusing on the most critical areas for compliance, you can follow these steps:

1. **Conduct a GAP Analysis**: Determine the extent to which your organization already complies with ISO 9001:2015. This will help identify areas that need attention.

2. **Establish a Project Plan**: Define activities, deadlines, and other relevant information needed to address the gaps identified in the GAP analysis.

3. **Plan the Audit Schedule**: Determine the frequency and timing of audits based on the importance of the processes and previous audit results.

4. **Plan the Process Audit**: Identify which processes are most critical and have the highest probability of nonconformities. Focus on these areas during the audit.

5. **Conduct the Audit**: Follow a structured approach to assess compliance with ISO 9001 requirements, ensuring that all areas of the standard are covered.

6. **Report on the Audit**: Document the findings, including any nonconformities or areas for improvement.

7. **Follow-up on Issues or Improvements Found**: Implement corrective actions to address any nonconformities and improve processes.

8. **Ensure Competence of Auditors**: Make sure that internal auditors are trained and competent, and that they do not audit their own work.

By following these steps, you can ensure that your internal audit plan is comprehensive and aligned with ISO 9001 standards.