We've gone on over and over the years about how one should use a password manager to ensure that you don't repeat passwords from one site to another, and I'm sure maybe one person in the world actually does this.
We try but it's difficult to succeed. But the fact is there are many passwords that are super popular and you should never consider using them. We have a link on our website to one list of such passwords including the most popular - one two three four five six. The second most popular, the word "password". I like the one - "Let me in". It's a great password. Don't use it. Don't use any of the popular passwords.
Instead you want to mixture of upper and lower case letters numbers and symbols, if your website accepts symbols. In addition many websites and programs allow you to include spaces in your passwords. So that you can include phrases. Not just single words. Making it more difficult for a password hacker to get into your account.
http://www.engadget.com/2016/01/19/worst-passwords-2015/