Most search engines determine most of the emphasis on the text content of your page. Keywords should be close together, dense yet meaningful with all your meta keywords repeated within the text.

For example if your website specializes in Toyota cars, you should have the word Toyota repeated as many times as possible in the text without that being obvious to the reader, even the search engine could detect a line of the word Toyota and will anticipate that you are trying to spam it. Do it but don't over do it and don't make it obvious.