It seems like every week a company releases a statement saying that customer data has been comprised. Customer data can mean anything from names, address, passwords, and emails.
The first step in keeping your credentials secure is to use a password manager. There are many password managers out there (e.g. LastPass, KeePass, etc). In 2017, LastPass revealed that the average company employee has to remember 191 passwords. Using a password manager eases that complication.
Another thing a password manager can help with is preventing password reuse. When you have to remember so many passwords it is tempting to re-use the same password. This can be a critical mistake, if you use the same password for your Facebook account and your Amazon account, then it only takes one of those companies to be breached for both accounts to be vulnerable.
Finally, it is advantageous to know as soon as possible when your account has been breached, for that I would recommend using Have I Been Pwned run by Troy Hunt. It’s a free service that monitors any email addresses you own, and when your account has been breached and an email is sent out notifying you. For example, I have had my own personal GMail account monitored for years and I was recently notified that MyFitnessPal was hacked and my email as well as other details were comprised.
In summary, use a password manager to prevent password re-use and alleviate the burden of remembering all your passwords. Then use Have I Been Pwned to be notified when your account has been breached.