Most important is to make sure to tell the team when you have no idea what you're doing. That way, that inexperience isn't going to surprise someone who is expecting something different. And ask questions! It means a) everyone knows that mistakes are likely borne of inexperience and not being bad at the game, and b) that you're willing to learn what is needed to make the raid a success. That's how I approached it on my first runs, and my teammates seemed very happy to help.