It seems like SEO is the hip new thing to be talking about, so I guess I should talk about it too.
What my clients do
When I'm working on a new site for someone, I do a few things to try to make sure that it is "search engine optimized" but it doesn't take extra effort for me or for the client. I ask them to create the content for their website and create titles that are descriptive. I ask them to get some periodic content (like a forum or a newsletter) about whatever it is that is important to their business or website. And that's it. The website should handle the rest of it for you.
What I do
Me, I just implement Drupal and in my theme and in the features I add to the site (my "module mix") I make sure to follow the Webmaster Guidelines from Google and some of the tips from Matt Cutt's blog.
The websites rank well. Sometimes for stuff I don't even want them to rank well. For example, on my personal calendar I have some classes I took at The Passionate Palette which is a great cooking school in Southern Denver. Depending on a variety of factors, my personal website ranks in the top 5 sites for the search phrase "passionate palette". I didn't do any magic and no fish oil is involved. Simply building the website the right way from the beginning gets this ranking.
Also note that this ranking is based upon content within my site - i.e. within my control. If someone is going to sell you a link exchange program to get better search engine ranking, ask them why they need to rely on a practice that the search engines disagree with.