Soul Resources
Hypnotherapy seems to be a gateway to learning about the soul world and a number of professionals have specialised in finding out more. Some people have very strong psychic connections and can talk directly with guides. They all have documented through books and on their websites what they have discovered. You can listen to interviews on YouTube to understand what they have learned, and some have also put their audiobooks on YouTube. Here are the ones I have discovered and found useful in my search, but there may be more.
I would suggest checking out their websites and searching for their videos on YouTube. It is impossible to list all of their videos here, so I have linked some of my favourites. You will find other spiritual leaders in Stress Resources.
Michael Newton
Clinical Hypnotherapist
Michael has written several books and there are a number of YouTube videos of interviews and audiobooks of his work He also has a website and trained hypnotherapists in Past Life Regression and Life Between Lives Therapy. His work is now carried on by the Newton Institute.
Michael's Journey of Souls is a must read for the beginner. It was mine and many other people's introduction to the soul world.