Try to think as your target market would if they were to do a search for information on a topic contained within your site. Do not just think about what people would do to find your site, but what they would do if they didn’t know your business existed and were looking for the types of products and services you sell.
Your current corporate materials, brochures, and other marketing collateral can be a valuable source of keyword phrases. Begin by indiscriminately highlighting any words that people might search for if looking for products or services your company has to offer.