1. Beware of False Claims - Beware of SEO's that claim to guarantee a #1 ranking on Google.

2. Don’t trust Secretive Companies - Ask for explanations if something is unclear. If an SEO creates deceptive or misleading content on your behalf, such as doorway pages or "throwaway" domains, your site could be removed entirely from Google's index. Ultimately, you are responsible for the actions of any companies you hire, so it's best to be sure you know exactly how they intend to "help" you.

3. Avoid SEO's providing "free-for-all" links - Avoid SEO's that talk about the power of "free-for-all" links, link popularity schemes, or submitting your site to thousands of search engines. These are typically useless exercises that don't affect your ranking in the results of the major search engines, at least not in a way you would consider to be positive.
4. Choose wisely While you consider whether to go with an SEO, you may want to do some research on the industry.

5. Keep a track on expense Be sure to ask any SEO your consideration on which fees go toward permanent inclusion and which to apply toward temporary advertising.

6. Use Reference References are a good start, but they don't tell the whole story. You should ask how long a company has been in business and how many full time individuals it employs. If you feel pressured or uneasy, go with your gut feeling and play it safe, hold off until you find a firm that you can trust.

7. Make sure you are protected legally For your own safety, you should insist on a full and unconditional money-back guarantee.

8. Beware of clever SEO's Some SEO's may try to sell you the ability to type keywords directly into the browser address bar. Most such proposals require users to install extra software, and very few users do so. Evaluate such proposals with extreme care and be skeptical about the self-reported number of users who have downloaded the required applications