Honestly, don't overthink it. Be honest and be yourself. If you have a sense of humor, let it show a little bit (I always like to). Ask them some simple questions to get to know them, and share some in return. I definitely wouldn't recommend avoiding them or keeping totally silent, because that can leave a bad impression. But at the same time, put a filter on your rowdier side if you have one (I made that mistake once).
Are you an introvert, or a shy-er guy? If it was me, I would definitely want to meet them while my girlfriend was around, to help bridge the stranger gap. Would that make you feel more confident? I would say to go with what feels best for your personality. Hoping for the best.