I would go back and encourage myself to upgrade my bicycle or at least get a bus pass- anything to start exploring and learning what freedom feels like at an earlier age. Younger me needs to go to libraries regardless if her parents think that "the library" is a lie that teen girls use when they go to meet boys in secret.
Also, I would warn her what kind of horrible elders her parents will wither into and how she's really better off not fearing them and their opinions in the long run.
Also, I would tell her to stop rejecting credit cards when banks offer them to her because it's going to be a huge hassle trying to build up credit from rock bottom way later down the road.
Also, save your money because the thing you REALLY want to buy hasn't been invented yet!!!