Advice for future prevention from being hacked?

Recently, I went through a pretty scary experience. I got an email from Gmail, that someone tried to sign in to my Gmail account and they were successful, that meant they knew my password. I don't know how, maybe I have a keylogger in my computer, maybe some other website got hacked and they got my password that way, maybe I typed in a sudo command in the terminal too many times, but the fact was, that they knew my password. I changed my Gmail password and set 2FA. And yet today I got an email that someone signed in and changed the email of my Instagram account, so I signed in, changed the password and deleted my Instagram account. One thing my Gmail and Instagram account had in common was the same password. It might sound funny, but today I realized that IT security is much more important than most of the people think. My question for you guys is: What would be your advice for me and for other people who are at risk of getting hacked to prevent dangerous future situations?

The measures I took after the hack was: 1. I bought a password manager subscription for a year 2. I have changed all my passwords to random and used a different password on each website 3. I have enabled 2FA everywhere it is available and bought a trezor wallet as a hardware key for 2FA