I ever read a description about making friends in a book which said"Before you are thirty years old,you can make all kinds of friends.When you are thirty years old,you should filtrate them to choose who can be your closed friends,who can be your common friends." I understand it as follows:Before you are 30,you have enough time,energy to make all kinds of friends.You can learn and know the society from contact with all sorts of people.When you are 30,you have your family,your steady job,your children,so you have to reduce your friend scope.And at that time you have your own worldview,valueview and outlook on life.So I think the process of making friends is a process full with continuous making new friends and continuous choice and filtrating.
I have two criteria for making friends if it can be called "criteria".One is that the person should have goodness heart.it means the essense of the person is kind.the other is according to my feeling when you are together with the person you feel happy,comfortable and easy.if so,we can be friends.these are baselines for me to make friends.