1. Ask the SEO firm to provide samples of past work or case studies on their results.  Reviewing their results can help you to understand how helpful their services will be and determine what methods they use to achieve top rankings.  If the firm you’re reviewing won’t provide samples, move on to another firm so you have some way of verifying the expertise and credentials of the people you’ll be working with.

2. Ask for contact information for two or three past clients.  Get in touch with these people and ask them about their satisfaction with the SEO consulting firm.  Even if the firm’s SEO strategy was successful, past clients may be able to tell you about communication problems or other issues they had with the company.

3. Interview the principal of the company to find out what SEO methods are used.  Stay away from firms that talk about using doorway pages, cloaking, and other unacceptable SEO methods.  Also ask about turnaround time, anticipated ranking results, and other indicators of how well the SEO firm will fit with your SEO strategy.  If you find a firm that meets your needs and seems to fit in with your company culture, try to work with them so you can optimize your site with people you like working with.

4. Avoid firms that promise number one rankings due to their efforts.  While a number one ranking MIGHT be achieved, the search engine rankings change every day so you probably won’t stay in the top position for too long unless you keep updating your site and adjusting your strategy.  Some firms will promise top ten placement, but no guarantees can be made as far as a timeframe for results.  Depending on your keywords, good results can take a few months or more than a year to achieve.

5. Avoid using a firm that promises strong results in a week or two.  SEO is a long process that begins with Web site analysis and never ends.  SEO strategies need to be tweaked constantly, so reputable SEO firms will tell you that it can take anywhere from a few months to a year or more to achieve top ten rankings.