I need help writing a SOW (Scope of Work) in which I am an external consultant who uses the mission-critical aspects of the organization to determine...

I need help writing a SOW (Scope of Work) in which I am an external consultant who uses the he organizations threats, risks, and vulnerabilities to achieve a holistic view of the risk across the entity. I do not know where to begin or how to write one. I cannot find an example anywhere that would allow me to see what all i would need to write on. The entity that I am focusing on is a government federal contracting agency. Can anyone help me?