The number one thing to have when getting your finances together is a budget. If you've never created a budget before, don't worry, it's not too hard. You should have minimal debts at your age (probably mostly wants than needs, I'm assuming?).
Basic budget: Income-liabilities=what you can save/use for discretionary money.
The hardest part that most people have is tracking all of their expenses and sticking to the allocated amounts for each line item. Since you'e not paying a mortgage or car insurance at your age, your budget should be super simple.
Does your high school have a personal finance class? If not, Duke has a course that is suppose to be free unless you want to buy the certificate. It's not for college credit and I don't know what this sub's opinion on it is. As long as it's totally free, it could be right up your alley. Enrollment ends today, if you're interested. I cannot vouch for the program, but it's Duke, so I don't have any worries about the content.
There's also a lot of great resources on the sidebar of this sub. This one is specific for your age: https://www.reddit.com/r/personalfinance/wiki/teachme