REFEDS offers a wide range of advice and guidance on best practice for research and education federations. This space is divided into the following sections:
REFEDS has created a document describing the value proposition for federations. This is a good place to start if you are considering implementing an identity federation and need more background information and support: The Value Proposition for Identity Federations
JISC created a Business Case document to help Identity Providers make the case internally for the work required to implement SAML. The document was written at the beginning of the UK Access Management Federation but is still valid and a valuable resource: https://wiki.refeds.org/download/attachments/7143427/JISC-business-case-toolkit.pdf
Understanding the Metadata Registration Practices of federations is key to understanding the trust framework for the federation. REFEDS and GÉANT have created a template Metadata Registration Practice Statement and federations are encouraged to use this template. This statement is a requirement for federations joining eduGAIN: https://wiki.refeds.org/download/attachments/7143427/MRPS-templatev0.3.pdf