nomis5 - 5:02 pm on May 8, 2012 (gmt 0)
There definitely are some basic rules that SEO companies can help you with if your site is very badly designed. Beyond that, SEO is now a myth in my opinion.
You, as designer of your site, are in the best position to SEO it. Look at where your site pages appear in the SERPS, compare it to those above and below you and do it every day for a month.
That way you will have the best knowledge about how to SEO your particular site. When you have SEO'd it and it rises in the SERPS, be prepared for it to fall again. The Google algo changes daily and major impacts occur monthly.
There are no "secret" SEO companies out there, keeping a low profile, which they have clients queueing up to use them. It's part of the myth. If you want it done well then do it yourself.