Characteristics of a strong password include a mix of uppercase and lowercase letters, numbers, and special characters to enhance complexity. Additionally, it should be at least 12 characters long to make it harder to crack through brute-force attacks. Avoiding easily guessable information, like names or birthdays, is also crucial. Passwords should be unique to each account, and using a password manager can assist in generating and storing them securely. These practices significantly enhance overall security against unauthorized access.