This is going to sound really fucked up but considering female physiology, what is the fastest wat to beat up a girl?

Do you punch her in the tits? Kick her in the pubic bone? The reason I'm asking is my sister got herself into a fight and she got fucked up by those hair pulling types off campus and they're going to get her again at school. Human physiology is scientific. I want my little sis to be able to drop those little cunts without hitting them in the head and them hitting the tile floor and killing them. I want her to be able to knock them on their ass. Staff will do nothing and she has until 8:00 am tomorrow to git gud. What are some movements and key points even a lanklet pleb like her could do and hit them without them being badly hurt and where she will exert maximum force? I decided to make this thread to get scientific information on human physiology for her. She will likely be shrekt tomorrow afternoon.