A link schema in DOORS helps provide control, enable analysis, and ensure consistency. It defines the allowed relationships between different information types, like how requirements satisfy other requirements or tests. The document provides tips for setting up a link schema, such as drawing out expected information types and relationships, planning links from later to earlier information, avoiding round trip or within-module links, and not using the default Links module. Analysis views can then be created and saved in DOORS to facilitate traceability and reporting across projects.