Substitution and Validation in Project System

Hi Everyone,

I have been asked to configure Substitution and Validation rule( In project definition, WBS , Network & network activity) for a company code and plant, both CC and plant  are already existing in the system. What are all the prerequisite we need to get from the Business before starting configuration and what are all the parameters we have to look out for  before getting kick started with the configuration.

Thanks & regards,

Ramprakash V