First to accumulating Bitcoin you have to look at the benefits and the rewards, it's not profitable to accumulate Bitcoin and then lose it to scammers or hackers so you ought to protect your funds no matter the amount of Bitcoin you can afford.

Firstly you can buy Bitcoin from centralized and decentralized exchange but personally I choose to buy from decentralized exchange because it protects my anonymity and other benefits.
But below is a list if decentralized exchange and centralized exchanges
https://bitcointalk.org/index.php?
topic=2906237.msg29885570#msg29885570

Also never leave your funds in an exchange that's why you need to have a personal wallet, I use cold storage wallet to save my Bitcoin because it's offline and more secured.

You can use this for educational tool about cool wallet setup.
https://electrum.readthedocs.io/en/latest/coldstorage.html

Security is very important, and how much or how to accumulate should not be complicated, always use yourself as the main subject you know what you can sustain a living with and what you can save up, so work with your income and as time goes you should grow.