You should have the same language, like the same topics of concern and hobbies, and it is best to have similar life circles and experiences, be sincere and generous, and be free. Don't talk nonsense and be reasonable. The most important thing is to respect each other and listen to each other. Don't make friends just to make friends. Don't be too close and dependent, be responsive and not too generous, and make fair-weather friends at the same time; Look at each other carefully, make friends if you are not an individual, and be careful not to be fooled. A hedge between keeps friendship green. Feel slowly. Good luck!