Content is important, but so is relevance. You need your ads to be relevant to your posts and this comes from keeping to a theme in your site. I'm assuming you have a blog, but this applies to other sites. If you have too many subjects you will get a scatter of different subjects for the ads. So the ads associated with an article on fishing may be on golf and no fisherman will ever click on them. Use relevant keywords in your article and you will get the right ads coming up. If after a couple of days you don't get enough clicks change the article. More advanced stuff is to try and use high Adsense value keywords. That way you will make more money per click.
Hope this helps,
Peter