Lol, I have no idea how to get into something like that. But I had to tell you that you made me laugh with "slaughter". My weird brain connected what you actually wrote and what you meant to write and now I have the image that the friend's daughter wants to be an extra in "slasher/horror" films haha.
That's a tough one, as even a good agency does not guarantee any work. Best thing to do is to contact a local film school and get some experience. Once she's done that and if she still wants to do this type of work then she'll have a showreel and some industry contacts.
Lol I read it as I'm investigating "a friends teenagers slaughter"
My mum has done some extras work through an agency. They're not cheap. She had to pay to be represented, a photo shoot, then a couple if hundred dollars for the prints. All before she could even get any work.
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