First, try to enter the classroom a few minutes early. If you are late, because there is only one door in the classroom, you should go in quietly and find a seat nearby. If the teacher looks at you, you can whisper "I'm sorry". Everything should be based on the principle of not disturbing others, but don't skip class because you are late. It's better to be late than absent from class. Generally speaking, students are free to choose their favorite seats, but it is suggested that foreign students sit next to local students as much as possible and introduce themselves first, so as to open their boxes and make friends.
In class, you can ask more questions to make the teacher feel that you have a sense of participation and know that you exist. Don't be afraid of your poor English and don't ask, and don't be afraid that your point of view is wrong. Asking mistakes is better than making mistakes all the time and not opening your mouth. When you want to express your opinion, you can ask the teacher's permission in a questioning tone to show politeness.
When introducing yourself, you should state your name clearly. Most Americans can't remember pinyin-style Chinese names, so taking a western name in advance can reduce a lot of trouble. As for the surname, you can pronounce it slowly and spell the letters so that others can remember it clearly. It is best to go to the bathroom before or after class. If you want to go to class, you don't have to raise your hand to ask the teacher's permission, just walk quietly and come back quietly.
Don't yawn and doze off in class, don't talk to others, don't eat (if you want a drink to refresh yourself, you'd better wait for other students to do the same), don't chew gum and don't read other books.
There are a lot of homework for studying abroad in the United States, almost every class. Some teachers may tell you the progress and homework of each class at the beginning of this semester, and some teachers may tell you in class.