Search engine optimisation companies are coming out of the woodwork every two minutes. It is extremely difficult to ascertain which ones are honest and can do the work for you and companies that are just dodgy con artists who might promise you the world, but never deliver. So for you to decide which company is for you is a difficult decision.
You first need to draw up a list of your requirements, what you want from seo consultants. Then you need to identify decent companies through friend referrals or through Google. Make sure they don’t ask you what you want to optimise for? They should be able to analyse your website and business and tell you what they think you should optimise for.