If you intend on entering into a Non-Commissioned Officer (NCO) role, such as a mechanic, then you will be entering the ADF via the General Entry stream.
The Defence Jobs recruiting process for the General Entry stream is the most basic of the recruiting processes. A diagram outlining the process and its relevant components is listed below. You will note that the writing in blue is covered in our aptitude training, and the writing in green is cover in our interview training (the OSB interview training can be applied to the Assessment Day interview).
If you are entering via the ADF Officer stream then you may be required to do some additional aptitude testing which will be scheduled in after your You Session and you will also be required to sit the Officer Selection Board which will be scheduled in after your Assessment Day. You will see these additions outlined in the ADF Officer Entry diagram.
As you can see it is quite a long process and without the proper preparation you are setting yourself up for failure. The Overall point of the Defence Jobs recruitment process is to screen out the applicants who are unprepared and unmotivated and find the ones who are willing to work hard and are dedicated towards achieving their desired profession.