Natural labor

I want to go into labor naturally, it's probably number one on my birth plan. I was induced with my first baby and it was very pleasant but it was really long and painful. My best friend who was pregnant at the same time as me went into labor naturally and had a 6 hour labor. I watch videos of natural labor and I want that so bad. I want to start right at 40 weeks but what are some ways to get my labor going so I won't go so far past due that I have to be induced ? I don't want to try castor oil.