When designing a site it's important to pay attention to the keywords from start to finish. You can use keywords in your domain name like seo-web-design-costa-rica.com and in your page names such as /SEO-Search-Engine-Optimization.
The keywords in the page name are far less important than those in the domains, but every little bit helps. Just remember that you need plenty of quality content in your site to backup those keywords or it's worth nothing. New sites should research keywords thoroughly and apply them where it counts.
Research keywords you say, how do we do that? The popular choice for years has been the Overture Keyword Selector Tool. You can see how often a certain keyword or combo comes up. This is useful to focus your pages on more obscure keywords. Obscure keywords are easier to rank in, and can often help you find your niche. If there are 50 searches a month for something it shouldn't be hard to be on top, but if there's 50 million then it will take far more than most business have to be on top. There's a lot more to researching and choosing keywords. For more information or help just comment here or contact me at sales@cr-sg.com. Pura vida!