Determining keywords is an art; it's best to work backwards. What would a customer search for if they were looking for your site? You literally have to put yourself in the consumer's place and let go of your preconceived notions about what you think your keywords are. You should remember when writing your site that you need to use words that are not only related to your content, but are popular search words as well. This is called keyword optimization, or choosing the most searched keywords related to your content.
