This paper explores the design and creation of metadata schemas based on the FAIR Data Principles. We provide a clear interpretation of these principles, focusing on how they apply to metadata schemas. Leveraging the OntoUML language, we developed a conceptual model that explains the key components of a FAIR-compliant metadata schema. Through detailed discussion and provision of examples for each model component, this work aims to help metadata designers and curators better understand how to incorporate the FAIR Data principles into their schemas.