The most important thing I've ever done in a meetup situation was to realize that I was not the only person there who was socially nervous. Before you do anything else, look around at everyone else in the group. Then realize that they all have their own insecurities, anxieties, and fears that they carry around.
Another thing that's helped me immensely is my posture, weirdly enough. When I stand up straight and square my shoulders and raise my head, I feel more confident.
Remember, you don't have to be the center of everything. All you have to do is show up and socialize, and most of all enjoy yourself.
Congrats for stepping out and doing something new!