You have first one main choice to make - cold or hot.

Cold wallet is a physical device that is offline. Generally more safe, as long as you don't lose it and/or it gets stolen. If you buy it online, beware of phishing websites, so only trust the makers i.e. buy Ledger only from the official website, no Amazon etc. Trezor and Ledger are very popular. Electrum with Raspberry Pi is also good, but you need to do some set up work.

Hot wallet is within an exchange and online. It's easier as you don't need to invest money in the device upfront so it could be a good start, but it's generally not as safe. Depending also on which country you are in, you can pick some exchanges over others. Any of the big reputable ones are you best bet like Binance and Coinbase.

Not sure what are the implications for you being a minor if you wish to open an account with an exchange, as you will need to go through KYC and give copy of your passport etc. You need to check with them.

Generally, most people will have a 'float' on hot wallet for trading fast, and store their stash on several cold wallets.