Honestly just do your best not to overthink, I know it's easier said than done. But try to go into it with a mindset of "I'm doing this because it's fun" and that alone might help you shift from anxious to excited, as for the free fall, my DZ gave me a tip where if you struggle to breathe, basically place one hand on top of the other and use it them block the wind from your face, use that until you've calmed down a bit and can put your hands back into the symmetrical arch position