As my understanding goes, nonfiction is different than fiction in the sense that you propose to the agent/editor the idea of the book and then you write it. (correct me if I'm wrong)

Now, my question is this - I can propose / pitch but what about those credentials?

I want to write a book on a legal/history topic, something that I did in my university and Masters but I have no credentials to back it up. Completely new to this.

Help please!