It seems like you know her, try to analyze her moves and the way she thinks, look for patterns or how she reacts when other people argue with her, try to observe what puts her down or what made her loose an argument with another person. Try to find a weakness in her, if you think she hasn't got one you are wrong, unfortunately you, me, her, we all have our weaknesses, just some people do a better job hiding it than others (so hide your weaknesses) one way to hurt your opponent is to attack when least expected. by attacking i don't mean physical, i mean psychological.
Well, I'm glad the teacher interfered. If the teacher had not stopped you from fighting then he or she could have faced a pay cut or been fired. And why should your teacher get in trouble with the school board because you decided to get in a fight? Fighting in school is no good!
In order to answer your question, I would need to know if you are a boy or a girl. If you are a boy, you cannot hit girls. Just get that into your head now. Yes, it sucks that a girl might slap you or push you to the ground, but as a boy you need to get into the habit of NOT hitting a girl back, because when you become a man you will be freakishly stronger than a woman.
Second, fighting in general, is a very bad idea. Whether it's boys fighting boys or girls fighting girls, fighting is only acceptable in a "sanctioned" sports competition or in a self defense situation. If you get in the habit of fighting with little or no provocation you are going to end up in the county jail or a state prison where you will soon be fighting with inmates who are a lot tougher than you. These inmates will take the food off your meal tray and you won't be able to do a damn thing about it.
Go up to her, saying you mean no harm and if she still attacks, be prepared and go for the feet. If you can get her on the ground your possibilitys are endless! You could always jump on her, but SHE HAS TO HAVE ATTACKTES FIRST IN THAT FIGHT TO MAKE IT SELF DEFENCE! But only do it if you're ok with getting in trouble, because no schools know what self defence is today. I witnessed a kid get punched and he completely owned the other kid, and they both got conducts. ( just something our school does )
Tell the teacher as many times as you can and if they don't fix it after a lot of trying then only if you fear for your safety take things into your own hands.
Okay so there's this girl in my class that nobody likes. She was bothering my friend, so I tried to help him out. So she ended up arguing with me, and she threatened to slap me. So I dared her to come over and do it, so we confronted each other and ended up arguing. So she pushed me down. I would've fought back but the teacher interfered. What should I do? It's technically self-defense, since she put her hands on me first. DON'T CALL ME IMMATURE, BECAUSE I'M NOT. SHE'S BEEN MESSING WITH ME LONG ENOUGH AND I'M READY TO FIGHT BACK.