Metadata plays a crucial role in making data FAIR. Repository providers choose and implement internal metadata schemas based on the specific requirements of their users. That said, we need a commitment and an implementation of a common metadata schema to facilitate synergy and interoperability between Earth System Sciences services and in particular to ensure interoperability between data repositories and NFDI4Earth central services, such as the NFDI4Earth Knowledge Hub. As a first step, we provide recommendations for metadata for Earth System Sciences that include a four-step approach for implementing a metadata schema and best practices for metadata.