PasswordGenerator.ME is a free utility to generate random passwords with ease, it will create strong passwords in the Web browser without sending them across the Web, which means that it's totally secure and reliable.
It's highly recommended to use passwords which have more than 15 characters, and contain at least one special character( e.g. #^&*)+ ).
It's a good idea to mix a password with a hash( MD5, SHA1, etc. ) string of a certain sentence of your own on the fly, then even if your passwords are stolen, they are still safe.
For example, bT(E=Z$GEB5Epw'U is your password, I Love Jane is your secret sentence, you can create the MD5 hash string of w'U I Love Jane and get 8624A742CD00326E2ECB89E39D56C9C7, then select a portion of the MD5 hash string, for instance, 8624A7, and compose your final password with them, which will be bT(E=Z$GEB5Epw'U8624A7.