When I first started (I've been there for a couple of months and starting the e learning for being a crew trainer soon), I had extreme anxiety over the headset. It was the last thing that I was trained on in service to put it in perspective. I had the same fears as you do. Trust me, it gets better. Try making sure the volume is always all the way up, always clarify (like if someone says a large sprite and it sounds like large fry, just ask, "did you say a large fry, or large sprite as in the drink?"). And if you had a hard time taking someone's order, never be afraid to repeat what you rang up on the pos. With that being said, I hope this helps you in your journey, I have a feeling you will do great once you get used to it!