I didn't have a degree but, when I got my E3 I had been around the industry for a while on top of all the usual studies for licenses ratings etc.
As bellthorpe said ,the interview is everything. Its not hard, treat it like you would an actual job interview.
Suit up, be organised, take paperwork for everything (and I mean everything) and act how you would expect a pilot to act. (confident and comfortable in your own shoes )
Although we Australians dont like to big note ourselves Americans are different.
You will also be judged by how you look and what you wear much more than what you are in Australia. Inside that consulate you are in the USA
enjoy your time in the the USA you will have a blast