Whatever the situation, the best advice is to obey the Golden Rule： treat others as you would like to be treated.
One possible version:
As the saying goes, “Treat others as you would like to be treated.” If we want to be treated well, we should treat others well too.
Two years ago, I was admitted to high school. Ranking first in my class, I felt proud and superior. Therefore, I dreamed about being admired and treated well everywhere, and I always looked down upon my classmates who turned to me in their studies. One day, Xiao Ming asked me to help him work out a math problem. I glanced at it, and said, “So easy, how foolish you are!” On hearing it, he said angrily, “I won’t ask you again and many classmates have fed up with your arrogance.” I was shocked. Only then did I realize why I was so unpopular with my classmates. From then on, I tried to treat them equally and helped them with all my heart. Time going by, I got along with them much better.
Keep in mind that we’d better treat others the way we would like to be treated.