For someone who knows little or nothing about SEO and Online Marketing it is difficult to make sure you are choosing a reputable company that will get you not just results but good results. Who you choose must also be an affordable SEO company, meaning that you actually see a return on your investment.
How long has the company been in business?
Have the company been around long, at least in Search Engine Marketing terms? Search Engine Marketing is a fairly new discipline, but many companies have five or more years experience. There are some good new companies with experienced people who have worked with online marketing elsewhere but there are also new companies who know little more about Online Marketing than you and will learn it as they go.
How many Examples of previous work can they show you and do they have testimonials?
To ensure you are using a company who really know how to do a good job make sure they have done a good job before. Many people will have examples of previous projects and explain what they did and what results they got. Testimonials are even better showing the business owner was happy with the work; you may even want to contact one of the companies they have done work for to make sure the testimonial is genuine and ask about exactly how good they were and whether it was an affordable SEO company.
Will the company meet with you in person or on the phone to discuss you objectives?