I stumbled accross this old-ish article (2004) from Shari Thurrow, a leading SEO consultant and director of US SEO and web development company Omni Marketing Interactive, regarding the skills to look for when selecting an SEO company.
In a nutshell, these are:
Clients will often hear me go on about how you will not find the requisite skills to build a great website in one person so I recommend avoiding having your website built by a single freelancer.
To generalise (perhaps slightly unfairly, but hope you get my point): designers tend to write bad code. Coders tend to do horrible designs. Its a left/right brain thing: different skills need different people.
We set up Reverse Delta to help combat bad web code. We are predominantly a technical company, but we know to outsource our design work to great designers who really understand the web, and not just the printed page. We also know not to let them do the coding!
We see web development as a production line. We start with architecture. Our architects understand both technology and marketing. We do keyword research to understand what words the target market are typing into Google. This influences the pages that we have on the site, and hence the navigation between those pages. We then get our graphic designers involved. They work in Photoshop to craft good looking websites. We then get our developers to build clean, standards-compliant code. Our Search Engine Optimisers are involved at every stage, ensuring their requirements are built in from the ground up. It is so much easier to build SEO into the foundations of your website than to try to “retro-fit” it. We have often been asked to optimise a poorly architected, poorly coded and poorly designed site. We have to explain that once you re-write the code, re-do the design and re-write the copy, there really is not that much left of the original site and it would be easier to start again from scratch.
As Shari quite rightly says, very few SEO companies have the right combination of marketing and technical skills. I am proud to say, I believe we are one of those few.