Keyword research is the most important part of good website marketing. Targeting the wrong keywords will cause you to lose valuable time, not to mention crucial sales.
Even though you think you know your products better than anyone else, you don't always know the lingo people are using to find those products. Remember, what may be common to you, especially when using slang or industry specific terms, may not be what your general viewing audience uses. Don't take for granted that you know what keyword terms people are using - spend a little money and buy a subscription to a keyword analytics tool. Most professionals in the marketing industry rely on a program called, Wordtracker.
Once you have your keyword analytics program, you are ready to begin the process of Keyword Discovery.