So to conducting an interview/casting.
With brand new girls it has to be done differently to experienced models. So to new models and how I did it since 1989, well before actually.
Explain the business to the interviewee and the work that is done in full, with pay, hours, etc. As much as possible and do it as yourself, don't adopt a false persona for the interview that will change when you pick up a camera.
Watch the interviewees reaction, eye contact, body language etc. You're looking for their reactions to what you want them to do and what the business offers. This is extremely important in most formats of porn. your work might be "Playboy" style and require the character and personality to bring it off. Or anal gang bang sex and you will want to know the interviewee has the character and personality to bring it off.
Then ask the interviewee if they have any questions and answer them. Then ask them what they would like to do. This will generally be a little less than they are willing to do, yet it gives the interviewer a great idea of what they got in front of them.
If a plain girl tells you she wants to do "Playboy" style, you need to let her down gently. A simple, "I'm afraid that's not for you, how about some solo girl "Amateur porn" work?". On the other hand if she appears dead nervous, scared of the whole thing and plumps for anal gang bang sex. you had best check out she can do it. Or risk wasting a lot of money.
What ever she says she can do, don't just accept it with an OK, find out before you start booking locations, other models and days to work. We were fortunate in having markets that would buy anything for their "Readers Wives" magazines or just the section in a magazine. so we could make money testing them. Even when not, you still need to know how they will react in front of a camera.
Same goes for boys, can he get wood when in front of a camera? Most men can't. Don't find out on the day of the shoot.
This is about producing better selling porn, not churning out scenes to fill the daily quota, good or bad.
Also as Herb points out my style hasn't needed to change much in 30 years. I'm still the same person, comfortable with how I work and it sells. Can the interviewee fit my format and style? Because there's no need to jump from style to style chasing the latest craze, when you have a winning format for you.
Good porn comes from sticking to a format and improving it over the years. Styles of hair, shaven pussies and clothing change. Sex hasn't changed since single cell amoebas split in two to reproduce. Nor has what gets a dick hard changed much.
Don't try to chase the affiliates craze. Follow your heart. Leave the
"What Niche is selling the best for you right now?" to those who don't have a clue what boat to jump into next.