Recently, it is evident that the economy of Europe is increasingly based on small and medium-sized enterprises (SMEs). To survive and be competitive in the market, SMEs must invest additional efforts in organizing their operations. For market sustainability and achieving satisfactory results, quality is an indispensable factor. This paper will provide a detailed overview of the standard ISO 9001:2015 – Quality Management Systems – Requirements, as the primary chosen tool for establishing a quality management system, aimed at delivering products or services that meet market demands. The development of the standard from its inception to the present will be described, along with how it has adapted to the increasingly complex market requirements. The goal is to explain the process approach and risk-based approach as the foundation of critical thinking and focus on quality. Furthermore, to maintain and continue developing a system established based on the standard’s requirements, and to strive for continuous improvements, it is essential to conduct its constant review through audits. The second part of the paper will provide an overview of the standard ISO 19011:2018 – Guidelines for auditing management systems, to clarify the requirements and provide guidelines for conducting both internal and external audits of the quality management system. In this paper, a qualitative model for the implementation of internal audits has been established, based on the integration of both standards in the form of an audit checklist and examples, in a medium-sized organization. The model addresses the risks associated with the audit as well as the issues and challenges faced by small and medium-sized organizations during the audit process.