Pretty much what Fire said. If you have half an idea you will breeze through the interview. The Navy is absolutely screaming for numbers so you have a good chance.
In the group activities if you are the extroverted type try and hold back a bit if you are the introverted type try to step up a bit. No one likes the highly opinionated guy. So just be somewhere in the middle of it all, offer your opinions, if you see an opportunity to take charge or a bit of leadership do so, but they won't be looking too much into that due to it not being an officer position.
Above all, know the job you are applying for in and out, know who the Minister of defence, the Chief of the Defence force and Chief of Navy are, touch up on a bit of Navy history, what ships are out there and the role of those particular ships. Know what the main weapon of the ADF is and know where the theatres are that we are operating in, it's not just the Middle East.
In saying all that, I never did group activities when I went through almost 8 years ago now. But I can't imagine the interviews have changed.
It's a great career. Here are just some of the benefits you can recieve.
- HPAS: ~$16000 first home buyers grant for all ADF members (you also still get the normal government grant of $7k, so about $23k all up)
DHOAS: Once you have served for 4 years the ADF will pay for some of your home loan repayments, 4 years service fetches you about $200 a fortnight.
Rent Allowance: If you are renting the ADF will pay just under half of your rent so in Ipswich QLD i recieve about $280 a fortnight for RA
Free medical and free dental
Don't pay medicare
Get to see the world
Get paid to keep fit
You also can get time off and cash incentives to study a degree.
I could keep going but you get the idea.
The Navy get paid the most out of the whole ADF due to seagoing allowance, expect to be away a lot living in close quarters. I did a little bit of time on Parramatta and asked myself how could anyone join the Navy. Each to their own I guess. I will say the Air Force generally treat their guys a lot better.
Hope this helps