1. Make an account at a *very* reputable exchange, maybe even in your country. Do a bit of research on which are reputable, what are the fiat transfer fees to exchange, what are the withdrawal fees from the exchange. Keep in mind that you may have to give your ID.

2. Start buying Bitcoin, but keep for now the coins at the exchange.

3. Do some research and buy a hardware wallet (HW). There are plenty to choose from, but you have to research and/or ask around to find out which on you'd prefer. After you receive it learn to use it (you can probably use with Electrum or maybe with its own software; it depends on your preference too), reset it a couple of times, then at some point write down (pen and paper, nothing online) a seed, copy/paste the first address, reset the HW again and this time restore from seed and check if the address is the same. Now you're good. That seed you'll keep very safe and offline. Safer than even your hardware wallet. An advice I've read is to keep it in multiple geographically separated locations.

4. From now on you can withdraw the coins from exchange to address(es) generated by your HW.

Keep in mind that withdrawal fees from exchanges are big and you may want to not withdraw too often.
Of course, if you do care a lot of your privacy, then you'll buy your HW first and learn to use DEX instead of the exchanges that ask for ID. But that may be a different learning curve.

PS. Afaik Metamask is about altcoins. If you only want Bitcoin I think that you can safely ignore it.