Trying to do SEO yourself is a foolish thing to do. It takes a lot of time and effort, as well as in-depth knowledge of the algorithms that drive the search engines. A professional marketing company studies the patterns that are causing ranking shifts in real time, and executes a strategy that takes the ongoing changes into effect, and bobs and weaves ongoing. There is no fixed process that defines SEO that works, every program is different based on the current needs of the client, as well as their individual competitive market. One SEO program may only need some inbound linking, while another may need an entire redesign and rebuild of the website. Some programs must focus heavily on "local seo" while others can expand to the more generic global search phrases. All in all, seo is a process of continual adaptation to the landscape, and only the best companies can navigate the waters effectively.