I know its no use posting "hi i'm 13, give me an acting job". It doesn't work. How do I look for jobs though?

I have seen millions of I'm 13 and I need a job, I have brown hair ect. I wish that would work and actually get you a job, but I know it doesn't. So how do you get a job? What do you enquire into? How do you advertise yourself? How do you get "big shots" to notice you? What should I look out for or search? But I will post my details so people kind of know who i am and what would suit me I'm 13, 157cm tall (don't know in feet ???) medium build with long straight blonde hair. Green eyes. I am into acting and singing. Mainly singing. But what would a young girl my age look out for? I am mainly doing it for experience, im not doing it for money so even if anyone knows free workshop things or voluntary stuff ect. that would help. Also side question, what do the people who hire you (directors, producers or people who "judge" you ect.) look for?