Help me find a cheap car insurance solution?

I’ve been hearing a lot of rumors about car insurance prices and stuff, and I really need some opinions. For example, I am 17 and I’d like to know if it’s cheaper to just put myself on my parents car insurance and use our junk car ( i don’t know what insurance company they use) or is it cheaper to get an old car of my own and put it on my own insurance like I’ve heard? All advice on car insurance is welcome, please don’t just limit it to the example. :)