Welcome to FT!

Here's my two cents:

Lots of people like Xanax etc, but personally I'd say skip it if you are already feeling nervous - feeling groggy when you want to be alert won't help. YMMV though.

Familiarise yourself in advance with your transit airports. If you need to change terminals to make your connection, know where you'll need to go and how to do it so you feel confident when you get off the plane (especially if delays make things a little tighter than you'd planned).

3-1-1 - if you are not familiar with the rules, take a look at them and make sure any liquids you take through security comply with the restrictions. Big water bottles are a trap for first timers. If you want water, get it airside.

IPad +1 - load it up with movies and books you love and the time will fly. Noise cancelling/isolating earbuds or ear phones are also a must.

Neck pillow - can really help with comfort if in Y. Also pashmina/shawl - better than a scratchy blanket and can be used for additional neck or lumbar support if you need t.

Turbulence - not sure if is is a concern but if it is, I find it can help to imagine I am in a car driving along a gravel/unsealed road. Most turbulence basically feels like this to me. And the tips about watching the FAs is right. If they are not looking nervous, you don't need to be either.

Luggage - keep it simple - especially your carry-on. Don't be the person lugging three heavy bags on board - it's too hard to manage and keep track of, you'll inconvenience other passengers and you might be forced to gate check. Streamlining your luggage takes a lot of stress out of the equation.

Allow plenty of time for check-in and to get through security. Worrying you might miss the flight will just add to stress levels.

You'll find we're a friendly bunch here in Australia - have a wonderful trip!