Do you need books for teaching materials or books for learning how to tutor privately?

Every tutor should know his/her students' individual needs and prepare accordingly. You don't need a specific book. It will only limit your creativity as a teacher. Find materials that are interesting to your students. Ask them what they want to know about. This will give you enough knowledge and ideas on how and what to prepare for each one of them.

You can find more tips here:
http://tutorsinc.blogspot.com/

Don't hesitate to contact me for further advice.