It is said that we don't choose a password but we build one. That is a valuable advice for those of us bent on increasing our password security. Choosing a password means picking a password that already exist. Choosing makes for week passwords. Building a password means we create a unique, random yet easy to remember string of characters.
Here are my suggestions for building a strong password:
1) Use at least 12 characters
2) Combine both lowercase and uppercase letters, numbers and symbols
3) For extra security use Unicode characters ( non keyboard symbols ) ex ☺(Alt+1), ♥(Alt+3), ♀(Alt+1+2), ♫ (Alt+1+4) etc. These characters are system/device specific.
4) Don't put numbers just at the end or beginning but also throughout the password
5) Use spaces if the system accepts them ( spaces are system specific )
6) Never use one password on more than two accounts
7) Never reuse a password
8) Never use personal or revealing information like your name, city, girl/boyfriend name etc.
9) Change it at least every 3 months
10) Never reveal it to anyone
11) Google for it to see how rare/unique it really is
Also some additional guidelines:
1) Always change a default password
2) Refrain from storing passwords in your web browser esp. on public computers
3) Always log out from current session, don't just close it esp. on public computers
4) Never use the keep me logged on function esp. on public computers
5) Always delete e-mails that contain usernames and passwords