Practice, practice, practice.
Be sociable everyday, talk to the postman, the shop assistant, people at the bus stop, just talk, about anything, the weather, what their plans for Christmas are, the latest news, about anything, people enjoy a conversation.
Their are some good internet resources and books out there for social anxiety, I would look into it.
Make eye contact, have a laugh, be charming, know about the other person, ask about the other person, say something relevant and relax.
Easy said then done, you need to keep socialising and talking. As the above poster mentioned, joining a club would help.
Good luck!