Hi monanaro, are you coming for college or HS? When I came to the US, I did not speak English at all. I was not taking English classes to learn it too. I had a Bio test the first day I went to school even though I did not speak English. So I just go to class and learn to study in English but did know any English beside what was outside of my books. I did not know foods name, game names, you know all the simple things that are essential in our everyday life.
These are some mistakes that I made and wouldn’t advise you to do so. When you first come, it’s ok to ask someone to repeat what others say in English to you in your mother tongue but don’t do it every day. It’s hard to understand the people when they are speaking, especially when they go to fast, but if you don’t have someone to interpret what they say for you, you will learn to listen to English and get everything by yourself. Of course you can ask someone to tell you if what you understand is correct. Don’t translate your notes into your language to study. Because the tests are in English, it’s better to learn your lesson in English. However this does not mean that you can’t put some little translation when an English word does not make sense to you. Your ego might hurt because the language problem might affect your performance during the first few month but you will be able to understand and write English after your first three months. Don’t hesitate to tell people to slow down when they are speaking to fast. Spent sometime with people who speak in English only, I know that you will be tempted to hang out with those who speak your language so you will feel more comfortable . Ask people to correct you if you make a mistake, tell them to teach you the pronunciation of words that you can’t say. The best thing I did before my classes was to read the material first, then translate some few words and look for their definition and reread it to make everything clear. When you go to class ready, you will understand more what the teachers will be talking about.
When you are done with an exam, get yourself a tutor and explain him the mistakes you make to see if they were done because of a language problem because sometimes you know the correct answer but you just can’t do well because some teachers play with words to trick you (specially in multiple choice questions)
But if you do that, your English won’t improve as fast as you would like it too. Reading and writing in English will help you too. When you find a word that you don’t understand, translate in your language, but try also to find it’s definition in an English dictionary so you can understand in which context they use it in English. You should always print your papers and read them to see grammatical and lexical mistake because it’s easier to see them that way than on the computer. If you find a buddy or a teacher who want to help you, you can chose a book to read, then meet with that person and talk about the book. Explain the story to the person.
At the beginning you might have more fun watching movies in your language but as time past, I would advise you to watch them in English without subtitle because if you put subtitle, you will just read them instead of trying to understand what they are saying. When you are watching tv, write new expressions down. If you have time to watch tv, watch news, documentaries and a variety of stuffs to have enrich your vocabulary in all areas.
Some funny thing: When people make joke, if you don’t laugh, it might means that you don’t get it but in order to hide your language problem, you might just laugh too even if you don’t even understand what they were saying. Caution: if the joke is about you ( LOL) you are in deep water
Your language barrier is not always negative. It can help you avoid a verbal fight with someone who wants to insult you. You can just say, excuse me , I don’t speak English and walk off. When you go to stores (clothes store), and sellers are offering to help you, you can tell them “ do you speak … ( your language) if you get annoyed by them and want to do your shopping alone. If you are lucky, they don’t speak it, they will leave you alone.
Don’t focus only on your Academic life, you will improve your vocabulary in various subject if you try to do things that are not related to your studies.
You can see that I still make some mistake in my writting but I guarantee you that the fact that you will just be living year will be enough to help you. Don't worry.
I hope that you will have a good time in the States