How to Win Friends and Influence People is well worth a read. It helped me start to think more about how to put myself in others shoes and ask, "how can I make this person feel good about themselves and important?" Focusing on that made it easier for me to approach people because it gave me some type of guidance on how to interact that made me a little less self conscious since I was thinking more about the other person.

(And I don't mean to gloss over that it is took a lot of work, but it was one thing that helped me. Best of luck!)