Never reveal your passwords to others.
Use different passwords for different accounts.
Use Multi-Factor authentication (MFA). Read more in this article.
Length trumps complexity. Complexity still counts.
Use phrase-based method: choose a password comprised of a sentence and put symbols between the words.
Use a combination of uppercase letters, lowercase letters, numbers, and symbols.
Use a password manager.
The best practice is to set up secure PINs and passwords to the phone system, such as voicemail access, extension lines, and other features that may be compromised if accessed remotely. Conference phones can also be a high target area, which is often forgotten about with poor usernames and passwords. If companies have a lot of passwords for multiple accounts as well as their PBX system, they might find it beneficial to invest in the use of a password generation and saving system.