A lot of people just publish their content and then find high traffic key words and begin to stuff inside their content. This kind of technique never works. When using keywords, they should come naturally in your article, that will hapen only when you find keywords and begin to develop contents around those keywords. The main idea behind seo is to appear on the front page of Google, but it is also true that you should write for real people, therefore, never stuff keywords.I have to agree that keyword is an important element in SEO issues because it is one of the main factors in the ranking of the site in the search engine results list. As what @Nomad above said, the keywords should be listed before uploading the new content that you will tag web page. If the web page is already uploaded then you will miss the opportunity. There is also the risk of keyword stuffing which means you cannot tag the new web page with a lot of keywords.