Ok, me and my sister are having a fued!?

Me and my step sister share a room, now, havent always, and we have like a totaly differnet personiltys, and we cant quit fighting. Help! What should we do? Shes at her mom's house on weekdays, were 2 years apart, and like our lives are totally differnt. Help, please help, i cant live another 4 years stuck with all this bickering.