Keywords must be both relevant and frequently used. You'll get them, but they won't do you any good. But its relevancy to marketing is questionable. Chances are, you are trying to sell a product or attract certain interest groups with your site. If you are selling marketing products or services, I sincerely doubt any of these visitors will be interested in your products.
Relevant visits equal more chances for sales and more chances for return visits.
In this section we'll show you how to select relevant keywords. In the following sections we'll show you how to apply them. This may not make sense now, but it will pay off later. Let's take the case of a site featuring water faucets. Well he's making several mistakes here and not taking full advantage of keyword power.