Use letters of different cases, mixtures of digits and letters, and/or non-alphanumeric characters
Do not choose a password based on personal data like your name, your username or other information that one can easily discover about you from such sources as searching the internet
Do not choose a password that is a word (English or otherwise), proper name, name of TV shows or anything else that one would expect a clever person to put in a "dictionary" of passwords
Do not choose passwords less than 8 characters long and that are made up solely of numbers or letters
