I know your problem,now let me help you.
Question One: You should listen to your teacher carefelly,and when you have something doesn't understand,you should ask your teacher or your classmate.
Quesntion Tow:Don't be shy!Try your best to talk with your classmate in English.
Quesntion Three:You should reviow your lesson before exams.Before you go to bed,say that"I can do the best!"
I hope this advice can help you.