I'm also shy. I don't know of any instruction manuals, but I'll offer a tip. When you go to the next hacker meetup, sit down next to someone and immediately introduce yourself. Maybe that's the end of the conversation, maybe it's just the beginning, but forcing yourself to verbalize with someone at the start of the event will make it easier from then on. It's also likely that the person you sit next to is just as shy as you and me.