Looking for instructions on how to create special user role types (e.g. superuser role)

Hello,

We are looking for instructions and best practices on how to create special user role types (e.g. superuser role) in Tridion Docs 13 Content Manager.  For example, we would like to create a superuser role type that has less permissions than the Administrator role but more permissions than an Author role.  

Any tips are greatly appreciated.

thank you

paul