I used to use to use automatic writing a lot. Im not sure if it does work as Ive never really wrote anything that was earth shattering so to speak.
Anyways you may like to try a book by Ted Andrews called Automatic writing. It may be out of print now, but it is a good little book.
When you try automatic writing take cautious steps to protect yourself and your environment, basically think of it like a ouija board.
You relax your mind and hold a pen on the paper. Sooner or later you will feel the need to move the pen. Dont force it or try to pre think what is about to be written. First up you may get some scrawl. If you get a lot put the pen down and leave it for another time.