What will fade my hair colour?

I have been dying my hair for about 8 months now and have do e int about 4 times. I am currently dark brown/black and I really want to go back to my original colour which is light brown/dark blonde, as I want to dye it blonde. I have been told I need to 'strip' the hair first, but I'm a bit weary as it can damage your hair. I was wondering if there were any alternatives that I could use ie head and shoulders shampoo or washing up liquid as I have heard these work, but my only downfall is it is so dark and I really want blonde hair!!!!!! HELP!!!