Hiring San Mateo SEO Professionals

Is there certain criteria I should be looking for when it comes to a San Mateo SEO team? I have three small websites that I would like to get better rankings in the major search engines. I used to think that I knew all about search engine optimization, but it seems to be that a lot of the tips and tricks that I once knew have now changed quite a bit.

I basically need an SEO team that will be able to help with planning, optimization and even putting together some campaigns that will be based upon content performance for my pages.