Take all the advice above and absorb it...first impressions are important. However for the meat and potatoes of the interview you need to remember some things:
They're going to ask you the generic interview questions: who are you, what is your background, where did you grow up, what would your teachers say about you (in high school and college)...etc. Nothing too elaborate, but they are trying to retrieve just enough information to get a snap shot of who you are, where your values lie, and what you've done in your past (which is an indicator of your character for the future)...basically figuring out of your character matches that of a Leader of Youth.
1. Your Interviewer is Human. Don't be afraid of them, but don't be too relaxed. The very realization that they are human, and you can talk to them, also means you may let your guard down. Don't. THis is where being a good judge of character and understanding human nature can be to your advantage. But always keep it right of center...neutral, if a little conservative.
2. Be Honest (but not too honest). Every situation should reflect you in a positive light, but don't embellish. Alternatively, if you have screwed up and made mistakes...DO NOT hide it, or dismiss it. ALWAYS make sure you show clearly what the mistake was, what impact it had upon you or others, and how you addressed it and either prevented it from happening again or what you've done to learn from it. I've known drug dealers that are now police officers...so take from that what you want, but know that they can forgive a LOT...but they can't forgive a LIE...
3. Take Your TIme. Answer the questions truthfully, but some may stump you. Don't just blurt out a bullsh*t answer. This is why you need to do preparation...understand the organization, have an idea of it's purpose, and look at what your purpose is, your motivation for getting involved with kids. The Recruiter is going to be assessing you for one thing: suitability to lead youth. If you appear to be flagging the answers, you'll get slagged by the Recruiter. THINK about your answer. FORMAT it properly. And deliver it TO THE POINT. Don't ramble, don't waffle...if the Recruiter requires clarification, he/she will ask for it. In many ways they want you to ramble, to waffle, so they can see if you will reveal something about your character. Just take your time, understand the question, and get your answer out.
4. Understand Harassment & Abuse. Understand CHAP inside and out. It's the meat of the meat and potatoes answers you will be giving. And it should be the core of your problem solving questions (how did you resolve a difficult or sensitive situation in your past...)...and it's easy to overlook. Ask about the processes of CHAP with your UHRA or CO. It will probably seem like a short, inconsequential question from the recruiter...but if you do not know how to deal with these situations properly it could be a deal breaker for you and the recruiter. Just use common sense, and don't offer opinions or an answer in an area that you're not familiar.
Just remember...as an Ocdt you're not going to be expected to have ALL the answers, but your instincts, character, and values should all point to one thing: suitability as a leader of youth. You want to give the Recruiter the impression they would leave their own kids in your care.
While some people will be better than others, they will let you know if they recommend you for enrollment and give you the reasons why (even if they don't recommend you). It's not rocket science, and I would say only the most disturbed people or those that "Just Don't Get It" would not pass the interview.
I know of no one yet that hasn't passed, so no worries.