I would recommend Healing Back Pain or Mindbody Prescription first because those are the roots. Then, the Divided Mind because other dr.'s weigh in. Lastly, The Great Pain Deception by Steve Ozanich because it really gets into your psyche, takes you through his real life story and success and gives you great tips.
Then, start with the Structured Education Program you can find on the TMS Wiki home page. From there, depending on who you are and what you need to do to heal you will find reccos for other books and help. Good luck!