Any Tips for Personal Trainer Interview?

to start off, sry if this has been posted a million times. I just got a call for an interview tomorow morning at 10AM at 24hour fitness. Im 21 years old and passed the NASM test about 3 weeks ago on my first attempt. I have no experience in training aside from the NaSM book and my own 3.5 years of experience in the gym.

i guess what im really lookin for is any tips as to what questions theyll ask. will they test me on my training? what clothes to wear? things like that. i was thinking just some slacks and a polo for the clothes part to help "show off" my work. by "show off" i really mean im not out of shape or have a beer belly or anything to hide like that.

thanks in advance to any feedback

Most gyms will hire you just because you have a cert and want a job. (Very few gyms actually care whether you're any good or not) Smart/casual is the way to go dress-style wise for most gyms.
They won't test you on your training, but do be prepared to say that you like "Functional training" and whatever the latest trends are etc etc etc.