The keywords chosen must be relevant to the content that is on the site being optimized. When someone does a search for a particular keyword they want to find content exactly matched to that keyword. The search engines want the searcher to find this content as well. Either the keywords being chosen for your SEO campaign need to match what is already on your website or the SEO consultant will need to create content that will match the keywords chosen for their relevancy to what services and products you provide.