Passwords need to be at least 8 characters long.  This is because hackers use computers to run every possible combination of keyboard strokes in brute force attacks.  As an example using the numbers on a keyboard only, if you have a one-character password, the hacker only has to attempt 10 tries to find the right one.  With a two-character password, the hacker must try 100 combinations (10 possible first characters x 10 possible second characters.)  With three characters, the hacker must try 1,000 combinations.  At this time, generally most hackers do not have the computing power available to run all possible keyboard combinations with 8 or more characters.  In order to randomly build a strong password that is easy to remember, one technique is to remember a sentence or phrase, then build the password out of that script: 

Example:  Phrase: Yes, I do fly a Fedex 757.  Password: Y,IdfaF757.

It is the best practice to use different passwords for each site you visit, but how do you remember all of them?  The best technique is to build a unique password for each site using a standard pattern.  The easiest way to devise such a patterns is to group a few characters that you can remember as a base password.  Examples might be your initials and birthday: John Q. Doe, born 7/4/76 might become JQD0704.  Then with each website, add something specific to that site like the first three letters of the company name.

Example: John Q. Doe, born on July 4th, visiting Amazon might use the password: JQD0704ama.  For eBay, the same person would use JQD0704eba.

To make this type of password even more secure, add a character to either side: !JQD0704ama!