Before you spend money on another network marketing course, it helps to hear from somebody who bought several. Esteban Ferreira reviewed the well known ones and stays specific about who wrote them and what is inside.
He is good on the credibility question. The course he rates highest comes from a woman who spent twenty years cold calling and holding meetings in living rooms, and who admits how often she nearly walked away. The ones he distrusts were written by people who never built anything and photographed themselves against a mansion and a sports car belonging to neither of them. Once you own that test you can apply it to almost any offer that reaches you.
The rest of the shelf is practical. A plain explanation of how a binary compensation plan works sits here, which is harder to find than it ought to be. So does a method for handling the person who says they need to think about it, and two posts for anybody starting a blog from scratch.
Read the course reviews before you buy, and the objection post before your next conversation.