Your interview is your interview -- they're all different.
I came from the Regs to the Reserves, so I don't know exactly how they run theirs. As a reservist, I dit OT. My interviews for that were done at the company level (for them to pass along their approval for a position) and by a PSO (for the trade). I was required to present my knowledge of the trade and the skills, experiences, and abilities I had that would allow me to excel in that trade and be of benefit to it. Upon my return to the regular forces, I had to undergo an interview again, this time with a recruiter whose trade I do not know (perhaps a PSO). Again, I was required to demonstrate my knowledge of the trades I applied for and illustrate how I would be of benefit to them. The one trade I wanted most, I didn't express my desire enough for and was called on it by the recruiter, and so did poorly on that portion of the interview (and did not get that position). The trade I wanted, pilot. Trade I got, armoured. All of them were during 1 interview session.
As with any interview, be open, be honest, be friendly and don't be boring. Don't lie, don't make crap up, go in knowledgable. Don't speculate, don't spread rumors, and don't believe rumors.