OK OP, I'll help.
Sorry about my english, not a native speaker, but what I am is debating mememagician.
There is no way to hide now. It's fight or flight, but you cannot flight your responsibilities at school and you shouldn't, so all that is left is fighting.
I'll give you short memory rule list, that if you follow you will do fine, and then I will give you a strategy and some tactical debating tricks.
1) Moralize! Large grouds work by psychology. With 1on1 discussions you can be more personal and talk about straight out facts, but in large debates where you are confronted by couple of assholes and many onlookers you need to appeal to emotion and morality. This is why you need a moral message. Donald Trump has his moral message: "Let's make america great again!" It's a possitive message not attacking anyone, and it's easy slogan, a meme material. As a national socialist, white nationalist, white separtist, etc you need to go directly to the core beliefs of your identity. I'll give you a slogan you can drop everytime someone morally accuses you of being an evil nazi racist etc. Just repeaat "whites have rights", and then ask what's wrong with whites having rights? Accuse them of hating whites. Always personalize their emotions. If they shout just point out calmly that their are irrationally emotional. It will russle their jimmies. Stay calm and have a moral message.
2) You are always debating for the growd, not for yourself or your opponent. So appearences are important. The most important is how you can take critizism and bounce back. If you can srugg all the accusations and angry shouts off like they were nothing it will impress everyone who isn't directly involved. You need to stand confident and strong, and have the ability to strike back verbaly.
3) Direct and amplify. This is not easily done in the middle of a heated debate, but everytime they make a possitive statement about themselve then you agree and say you want that too, or if they are speaking about hating racism or suppremacy, then agree with them. You can take historical examples of non-whites doing bad things, but also you can bring up the jewish slave trade in pasific triangle trade. This can win people over, but most of all it trows them off. Agreeing with your opponent and butting yourself and your ideals alined with them works like charm.
4) NEVER SAY SORRY! NEVER APPOLOGICE! You can play dumb, but do not say sorry. You do that it's over.
5) Playing stupid but coming back sarcastic is a working strategy. Never start with this. Play intelligent and open minded, so people listening you are well aware when you play sarcastic an when you are serious. It's wrong to start sarcastic when people don't have a reference of you being serious. People can misunderstand your sarcasm if you start with it. When you see a logical inconsistancy in your opponents argument, and deside to go for the kill, then you can try to lure them to logically admit cognitively dissonant premises and attack them.