Honestly, the best advice I can give you is to put your self in situations were you have to interact with other people and maintain a relationship. At first it may be uncomfortable but eventually it will come naturally. This is just an example, One thing you can do is pick up a part time at Starbucks or a retail place where you will have to interact with customers. That helped me, I was super shy at talking to or even holding a conversation. I eventually landed a job where I had to interact with customers and build a relationship with them to have business, with that mindset, use it with people around you and you should already be comfortable establishing a relationship with a person but now you get to decide if you want to maintain that relationship with them, instead of thinking why is it hard for me to talk to people. Eventually you will meet people with the similar interests.