The best and easiest way to determine whom you were in a past life is to visit with a past-life regression therapist (hypnotist) who can take you back before you were born in this life.
I did this a number of years ago with surprising results. My entire life, I have suffered a constant, nagging cough. During this past-life regression, I learned that I was an adult woman in Boston. My husband and I had just returned home in a horse-drawn carriage, so I figure it must have been at the end of the 19th or beginning of the 20th century.
While my tall and handsome husband left to help tend to the horses, I climbed the few stairs up and into our home. Upstairs, I got undressed and ready for bed. As I was changing, someone grabbed me from behind and began choking me. I came out of this session coughing like crazy and since that day, I no longer have that constant, nagging cough.
I believe we carry some dramatic things over from past lives and fortunately, I was able to get rid of this problem.