Friends come and go, but there is really only one secret in making a best friend one you will treasure for life.
Looking for those people:
Over 7 billion people in this world, and you can't find a single friend? If that's the case, maybe the problem isn't other people, but the way you approach them. Once you get the ice breaker out of the way, you can engage with that person over many topics. If the person doesn't want to cooperate or is not interested in talking to you. Then move onto the next person. Eventually, after like 100 people, you will find someone you can talk to and have a normal conversation with. Sometimes you also need to exit your comfort zone to meet different people. There are two terms to explore for this. Extroverts and introverts: where extroverts are people who love to be outside and hangout to socialise, while introverts are the exact opposite. For both types of people, the topics to talk about vary, but if you are a balanced person, you shouldn't have a problem enjoying the company of other people in general. For extroverts, they will find people in places such as parties, bars, social events, and trips. Whereas introverts find people on social networks, online gaming, maybe libraries, and work (if they like their job). For extroverts though, they have an easier time determining if the person will be a great friend because obviously they are physically there. Whereas introverts can't really determine much unless they talk on voice chats and video chats often. Another place to find people, is through events such as a concert, convention, and possibly college because at least there you will share a common interest which fits well whether you are an extrovert or introvert. Now you know how to find people, but remember to not be annoying, but do be persistent in talking to other people, even if you are an adult. You will be much happier knowing there is someone who shares the same interest as you. If you are in a relationship, inform and ask about it from your partner or spouse.
Swim for a conversation:
Now that you found someone who is willing to have a conversation with you, you can start off slow with some basic small talk. The most famous technique for talking to new people is the FORD technique, which is talking about: family, occupation, recreation, and dreams. It's an easy way to start if you really can't figure out what to say first after your icebreaker and introduction. Now I want to talk about a technique that I like to mention. So in swimming, there are different types of dives. You want to save the best for last so just go with a normal forward dive about anything you did in your life. I would rather want to have a first stale conversation and save the more interesting things to share for when you go on dates or so. Now, if they are the hit and run type of person and they hit you with a crazy twisting dive with many somersaults, then you have no choice but to do the same, because normally they will only stick around if you are extremely interesting. You can also determine if the person is either an extrovert or an introvert depending on their interaction with you. When you do part ways, it is entirely up to you if you want to continue having a conversation with them, but when you feel like you are the one initiating the conversation all the time, then just let them go and find another person. That person probably isn't interested in you and doesn't want to be your best friend.
The Trust of Friends:
There is a saying for a friend is someone that will lend you a shoulder to cry on, despite that cheesy saying, it is true. For introverts, finding a best friend is tough compared to introverts because of our lack of meeting each other physically. Being with someone and taking time to meet, is part of building trust with your new friend. At first, you both might suspect each other based on previous friendships or experiences, but don't worry as every experience will be different, there is no such thing as experiencing the same thing more than once, because each time you will handle each situation differently. Even if sometimes you both have different opinions and activities, if you are willing to explore together, you will also be learning new things naturally than if you did alone. In the matter of the fact, when you have many interactions with many people you will figure out what you like in a person, on the contrary to having many friends, you will never have lots of best friends. A best friend is someone that knows how to keep promises and be able to organize their busy schedule to be with you. That is the true difference of trust between each level of friendship. When you notice that the other person is willing to do that for you, you should do the same in return. There is also many examples in the book titled, "The Best of Confucius: Confucius' Lessons for Life Changing Success", which you might want to look into reading. By both of you making sacrifices for each other, your trust will strenghthen.
Unlike family, a best friend is someone you can go to to talk about things you don't want your family to know about. When you are experiencing a rough time in your life, and sometimes you feel that even your best friend doesn't understand you, maybe you may need some time alone, but do tell your family and them about it. That way, when you feel better, your best friends will be back at your side waiting to accept the new and improved you (stay away from having negative thoughts and resorting to drugs). Knowing that your best friend is their for you even when you were feeling down is a great feeling you will have to experience for yourself.
You will have many friends, but best friends are people you can trust with your life. Find those people you can invest your time into and don't be afraid to leave your comfort zone.