To develop an internal audit plan that aligns with ISO 9001 standards, focusing on the most critical areas for compliance, 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 achieve compliance.

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

4. **Plan the Process Audit**: Identify which processes are most critical and have the highest probability of nonconformities. Focus on complex processes and those that directly impact quality.

5. **Conduct the Audit**: Execute the audit according to the plan, ensuring objectivity and competence of auditors. Use a checklist to cover all requirements of the standard.

6. **Report on the Audit**: Document audit findings and communicate results to relevant management.

7. **Follow-up on Issues or Improvements Found**: Initiate corrective actions for any nonconformities and track improvements.

8. **Conduct Management Review**: Review audit results and decide on readiness for certification audit.

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