The more acquaintances you have, the more opportunities will be available to you. In fact, studies even show that you are more likely to get a job through an acquaintance than a friend.
Every acquaintance you have will give you access to a new world you would otherwise be unable to be a part of. By cultivating more acquaintances, you increase the chances of achieving success.
Be confident, sociable, energetic, and curious.
Introduce yourself to strangers and hold meaningful conversations with them. Aim to incorporate the above into your character and personality.
Maintain meaningful contact with many people.
Take the first step and call your old friends every once in a while to catch up. It is tiring to devote time and attention to many people, but it will pay off.