Advice for My Younger Sister

I want to share my experience of being a young woman and communicate to my 15 year old sister that she does not need to conform to society's rigid and box-like ideas of how she should behave and act. She does not have to shave her legs or smoke in order to be accepted. I also want to encourage her not to overthink or worry too much, and to avoid being self-absorbed, that never leads to anything good. Instead I would like her to be confident and herself, and in time everything is going to be alright.