To be able to create a complex password, you have to use the upper and lower case alphabet, numbers, symbols, and punctuations. But the question is, how the hell am I going to remember it? Once you learn the secret, it will be easy as pie. You can even have different password for every account that you own once you learn the secret.
L337 or Leet also know as leetspeak is an alternate alphabet where you replace letters with simmilar looking numbers, symbols, or punctuations. For example, "Bananas" would become "B@n@n@$", a more complex example is "Tomatoes" would become "70m@+03$".
Use abbreviations or shortcuts
A shortcut is a 1-3 character letter or number that can be used a an alternative spelling to a word. For example, "who" can be "hu", "you" can be "u", "to" can be "2", etc.
Find your favorite phrase and abbreviate or shortcut each word to create a short version and use capital letter at the beggining of each word. For example, "Who you gonna call? Ghostbusters!" can be "HuUGC?GB!".
Common Rule for Multiple Password
The next step to further secure yourself is to have a different password for each of your account. It is dfficult to memorize multiple passwords if you randomly select words or phrases as your password for each of your account. The secret is to have a common rule with your password and use your service provider as a hint for your password.
One example rule is that you use a common password but you prefix it with your service provider's first letter and suffix it with the first letter of the second syllable. For example, my common password would be "Abc*123" then my Facebook password would become "FAbc*123B", Yahoo would be "YAbc*123H" and my Google account would be "GAbc*123G". Just make sure that the subtle changes in your rule are not that obvious (e.g. "Abc*123_FB") or the hacker can easily guess it.
Another variation of the example given is to use the service provider as a prefix and middle character. For example, Facebook password would be "FAbc*B123", Yahoo password would be "YAbc*H123", and Google password would be "GAbc*G123".
Another example rule is that you use a common password, next is you look at the service provider's logo and pick the color that catches your eye the most and mix that color spelling with your password. For example, Facebook color is blue (B1u3), my password will be "BA1buc3*123"; Yahoo color is violet (Vi013+), my password would be "VAib0c1*31+23"; Google color is red (R3d), my password would be "RA3bdc*123". This password is difficult to remember but what you can do is type the common password first, move to the beggining of your password, and spell the color while pressing the right arrow after typing each letter. Note that this password is difficult to use with mobile devices where keyboard is not available.
The example given is not a general rule, you can be creative with your rule as long as it is easy to remember and difficult to guess. It is important that you do not reach the point where you have to write your password on a piece of paper beacause it is too difficult to remember.
Mix em up
To make your password more complex, you can combine L337, abbrevations, and shortcuts. For example, "Happy Birthday to you, Joe!" can be "HBD2U,J03!". Don't forget to add your common rule to have different passwords with each of your account.
Your password should be at least 8 characters long to make it more secure.