How do you make friends?

Why do I always lose my friends and end up being alone. So I am always able to have a friend in starting but the point someone else joins, after some days they start making fun of me including taunts and little bit hate. I am a normal person and always help others. This has happened in my school days, college days and now in the professional world also. I am asking this question because I have got really alone. Guys have you observed this kind of person? Please tell what he can do to get some friends. I know I may not get answer to this but please know that it hurts when in trio you make fun of the same person. (Some of my background: I have been probably district topper and sometime a very good one digit rank at state level also but I never discriminate people.)