I would second the Brian Weiss material. He has some good CDs for intro exploration into past lives.
I had a hypnotherapist introduce me to one of my past lives and I created the intent that a door be opened so I would have access to all of my past lives. Since then, I have explored quite a few of them without ongoing professional help
Nearly all hypnotherapists can do this type of thing, but if you PM me I'd be happy to share the contact info for the hypnotherapist I used. He is in Long Beach.
--sjkted