Password strength is a measure of the effectiveness of a password in resisting guessing and brute-force attacks. In its usual form, it estimates how many trials an attacker who does not have direct access to the password would need, on average, to guess it correctly. The strength of a password is a function of length, complexity, and unpredictability.
Using strong passwords lowers overall risk of a security breach, but strong passwords do not replace the need for other effective security controls. To choose strong passwords follow the following steps:

Step #1: Make it Lengthy

Make sure your password has eight or more characters since this is usually the minimum for most password requirements. The longer the password the better.

Example: mystrongpasswordissecure


Step #2: Add numbers to your words

Example: strongpassword2291


Step #3: Use special characters

Example: password$$200


Step #4: Use upper and lowercase letters

Example: PassWord$$200

Step #5: Generate similar but altered passwords. Use the same or similar base-words to help you remember your passwords easily without making them "too" easy to crack

Example: PassWord$$200 can become *200WordStrongPass$$