2. Make long, unique passwords, and never reuse them. Complicated combinations of numbers, uppercase, lowercase letters, and symbols make the most robust passwords. Reusing them is never an option — if one account gets hacked, other accounts are at risk.
Article source: https://www.huffingtonpost.co.uk/entry/weak-password-open-to-hackers_uk_637e2975e4b006c42d3a09c7