It depends as usual. Do you want to do something that involves math? Then you'll need Algebra. Still, you can teach yourself on the Internet, and no teacher in a government school is needed.

What are you passions? What are your natural talents? If you don't know them already, go out and figure them out. Ask your friends what they think you are naturally good at.

Do your best to not waste your valuable time. It's your life after all. Tick tock, tick tock! I wasted 20 years of my life on a hamster wheel doing Information Technology work, and I hated it the entire time. Don't do what I did.

Follow your passions, set goals and achieve them, and learn things that are valuable no matter what you do (liberty, economics, languages, etc.)