Switched has a great article on passwords that everyone needs to read. It covers all of the basics — long passwords, random passwords, special characters, etc. Another trick is to use something about the site and add it to your standard password.
For example, lets say you always use “red” as your password. For yahoo.com your password would be yahoo.com_red. For google.com it would be google.com_red, etc.
Personally I like using the first letter of song lyrics. For example, “I went down in a burning ring of fire” would be Iwdiabrof.
