In my experience you should handle SEO yourself. Most of these guys are a joke (but not all). There are a couple of alternative strategies SEO's use like hot be

In my experience you should handle SEO yourself. Most of these guys are a joke (but not all). There are a couple of alternative strategies SEO's use like hot beds, link farms and other white-hat / black-hat techniques... however, most of this stuff is on Google's checklist to weed out over time as there jeopardize the integrity of AdSense too. And quite frankly, if you have to stoop this low you shouldn't be in business. One of the most important things is getting linked-to by respected sites (ie: TechCrunch) and amongst the web (PR releases but do these sparingly). It's in this dimension that page rank within search results are determined these days, a natural filter to all the crap! This is key reason why spam bots dump responses filled with links on blogs and popular sites like Digg/etc... Bastards!! However, it's still in good form and highly recommended to continue using UNIQUE meta tags, page titles, alt descriptors, etc... And, there are valid white-hat techniques to consider, especially if your site is entirely flash/flex or graphic-heavy in nature. An example of this is delivering GoogleBot an alternative page that your visitors do not see which describes the site's content by way of traditional markup. Mismanaging this can quickly put you in the blackhat bucket. Sitemaps are also important and I don't see enough sites trending to spider's preferred structure: sitemap.xml. Drupal users are in luck as there is a plugin to handle dynamic generation of the sitemap to spec, and submits it to Yahoo/Google/Live spiders each time your content changes. But if you don't use Drupal, just google "sitemap.xml" and you'll find out all you need to know. Speaking of Drupal, search engines absorb it like a sponge; it's soo well built for SEO. <3 :P