Maybe you are sensitive and even afraid of failure. The hardest part is actually at the beginning, when I am free, I make friends with my classmates and make excuses to say, how to do this problem? Or buy some snacks for your roommate. Also, don't care too much about what others think of you. Speak boldly and do boldly. People who don't talk to you may think you are aloof. Don't always hold a serious expression in life, but keep smiling. People think you are easy to get along with.