Don't BS, and be yourself. For better or worse, that will go a long way to an employee being able to assess you for the job.
If you dont know the answer to law questions, know where to look. PDF docs on an Ipad are an easy way to get them around. If you don't know the answer to other questions, don't BS. Do your homework, you wont have to make stuff up
Have questions ready based on what you have learnt about the operation.
Apart from showing professionalism, interest and intent, it will show you have done your homework.
Know at least the basics of aerodynamics/Lift formula/pilots lift formula/Critical angle.
Know the rules pertaining to your current work.
If you know the aircraft the company flies, get your hand on a POH if possible and have a read. (prob wont be asked in early interviews, but you never know)
Dress sharp.
Why do you want the job
Where do you see yourself in 12 months/ 2 years / 5 years?
Do you need to give notice?
Are you flexible with working hours (you'd wanna be!)
PNR/CP
Do you have accom lined up/how long have you been in town (Operators up north/outback etc might wanna know you can deal with the difference outback living can deliver?
If its not specifically listed as "the award" or the pay is not clearly stated, make sure you ask about the conditions (all of which are available from the AFAP website.
Good Luck