Hi - getting her into a good theatre group or acting class would be a good idea, and if she doesn't already, having singing and dancing lessons is advisable.
Starting acting at 13 is difficult - most jobs for teenagers go to kids who have been at major stage schools since they were 6, but very few of them manage the transition to adult acting.
I'd advise that she gets experience at the theatre group, and works really hard at school to get good enough grades to get a place in a top drama school when she's 18. Everything she learns at school will be useful for her as an actor - it all seems to come in useful when you least expect it.
After drama school is when she'll need to build up a resume, because the experience they look for is in adult's plays, short films, etc, not kids' stuff.
Do make sure that this is her dream, though, not yours. Even if she has real talent, it's a very hard life, and she'll probably never earn much money or become well-known. Most actors have a 'normal' job for the huge gaps in between acting work, just to pay the rent, the bills and food.
She would have to want it more than anything and be prepared to work really hard for many years before she gets a single paid job.
I'm not trying to be negative, but being realistic is essential.
My daughter's just finished drama school, and is at last starting to get work, but it's not easy.
I wish you both luck!
xx