Just using a keyword is not going to rocket you to the top of the search engines. Knowing what keywords to target is essentially one of many pieces of your SEO strategy. Once you know the keywords that you are targeting you need to use in the right place and on the right page. Keyword prominence is one of many factors that come into place. Basically, you should always try to target the beginning of your title tag and paragraphs to put keywords that you are targeting on a page. So technically, [Keyword] [Rest of your sentence] beats [Rest of Sentence] [Keyword] and [Keyword] [Sentence] [Keyword] in prominence. The same applies to paragraphs, and tags. It’s such a small thing that many people forget about but apparently it is very important to search engines.