Core avocates

Taking this camp 36-12-3 and it talks about having some core avocates in your data base. I have none. Been thinking about who and how to add these core avocates, i realized its just talking with them and getting to know them very well. Also to ask for the business and treat them extremely well. So with that aha moment, i need to learn how to communicate with people on a new level to get me where i want to be with future people, clients, customers, and friends. Does anyone have any suggestions on a book on communication skills? (its not that i cant talk, i just want to talk better)