I have a few tips
Take a pillow with you and hold it on your lap. you can hug it too, it is pretty comforting and gives you something to hold.
Look on you tube at the former backstreet boys member, who went on Oprah and had a full on panic attack. Whenever I am out I think if he could go on national TV in front of a huge audience AND panic and he was fine then I know I will be fine.
Take something from home that you take comfort in, like a stuffed animal, photograph etc.
Take a bottle of cold water!! this is important as you can splash some on your face to calm down.
Look online for soothing visualizations and copy some to your phone that you can listen to in order to keep calm.
If you panic, remind yourself that you are in no danger and that it will pass in a few minutes and then you will feel that rush of calm which is always awesome.
Take a few apples with you to chew on
Use your phone or take a camera with you and take pics of anything to keep yourself distracted. This helps a lot and the pics can be of anything.
Take some chamomile tea in a decanter to sip on, it is calming
And most importantly, have fun!!! Anxiety is just the same as excitement but we interpret it differently, so interpret it as a fun outing.
Hope it goes well, and remember that the anticipation is always worse than the actual event.
Have a great time