In order to get a friend you must BE a friend. Consider all your acquaintances as friends. Now try to BE a friend to each one of them, without any expectation of return. Treat each one of them as YOU would wish to be treated. Most people will reciprocate. A few will take all you have and return nothing - drop those ones quickly. The rest should form a good circle of friends for you. You may or may not find a "best friend" in that circle.
If you do not have many acquaintances, then go to the places where you will find people. Take a class, join a sports group, join a reading circle - whatever you ENJOY doing, that is also social and make a point of being friendly to everyone. Not over friendly but pleasant and helpful.Take your time over this, don't try to rush it.