During an ISO 9001:2015 internal audit, best practices include ensuring auditors are competent and impartial, preparing a checklist based on the standard requirements, and planning the audit schedule and process. Auditors should focus on complex processes and areas with a high probability of nonconformities. After conducting the audit, results should be reported to relevant managers, and follow-up actions should be taken on issues or improvements found.

Nonconformities should be addressed by controlling and correcting them, evaluating the need to eliminate their causes to prevent recurrence, implementing corrective actions, reviewing the effectiveness of these actions, and making necessary changes to documentation.