Any SEO company that is halfway worth its money should be able to rank organically towards the top of a Google search. You may perhaps want to skip the agencies advertising at the very top of your results – they just try to skip the line. Beyond that though, we would just give you the same advice as for most other services you are looking for: look at reviews, look at their website, contact some companies. Get a feel for which one is right for you. We think Marketing Blendz is pretty good. But then again: we may be biased.