Read the original Google Search Engine Optimization article here.

SEO is an abbreviation for 'search engine optimizer'. Many SEOs provide useful services for website owners, from writing copy to giving advice on site architecture and helping locate relevant directories to which a site can be submitted. However, a few unethical SEOs have given the industry a bad name with their overly aggressive marketing efforts and their attempts to unfairly manipulate search engine results.

While Google doesn't have relationships with any SEOs and doesn't offer recommendations, we do have a few tips that may help you distinguish between an SEO that will improve your site and one that will limit your search engine opportunities alltogether.

Be wary of SEO firms that send you email out of the blue.

Amazingly, we get these spam emails too: "Dear google.com, I visited your website and noticed that you are not listed in most of the major search engines and directories..."

No one can guarantee a #1 ranking on Google.

Beware of SEOs that claim to guarantee rankings, allege a "special relationship" with Google, or advertise a "priority submit" to Google. There is no priority submit for Google. In fact, the only way to submit a site to Google directly is through our Add URL page or through the Google Sitemaps (Beta) program, and you can do this yourself at no cost whatsoever.

Be careful if a company is secretive or doesn't clearly explain their intentions.

Ask for explanations if something is unclear. If a 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 understand exactly how they intend to help you.

You should never have to link to an SEO.

Avoid SEOs 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.

Some SEOs 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.

Choose wisely.

While you consider whether to go with an SEO, you may want to do some research on the industry. Google is one way to do that of course. You might also seek out a few of the cautionary tales that have appeared in the press, including this article on one particularly aggressive SEO: Internet Advancement told to refund clients

While Google doesn't comment on specific companies, it is not uncommon to encounter firms calling themselves SEOs who follow practices clearly out of scope of accepted business behavior.

Understand where the money goes.

While Google never sells better ranking in their search results, several other search engines combine pay-per-click or pay-for-inclusion results with their regular web search results. Some SEOs will promise to rank you highly in search engines, but place you in the advertising section rather than in the search results. A few SEOs will even change their bid prices in real time to create the illusion that they control other search engines and can place themselves in the slot of their choice. This scam doesn't work with Google because their advertising is clearly labeled and separated from the search results. Be sure to ask any SEO you're considering which fees go toward permanent inclusion and which apply toward temporary advertising.

Talk to many SEOs, and ask other SEOs if they'd recommend the firm you're considering.

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. Ask your SEO firm if it reports every spam abuse to Google using the spam complaint form: Spam Report. Ethical SEO firms report deceptive sites that violate Google's spam guidelines.

Make sure you're protected legally.

For your own safety, you should insist on a full and unconditional money-back guarantee. Don't be afraid to request a refund if you're unsatisfied for any reason, or if your SEO's actions cause your domain to be removed from a search engine's index. Make sure you have a contract in writing that includes pricing; the contract should also require the SEO to stay within the guidelines recommended by each search engine for site inclusion.

What are the most common abuses a website owner is likely to encounter?

One common scam is the creation of 'shadow' domains that funnel users to a site by using deceptive redirects. These shadow domains often will be owned by the SEO who claims to be working on a client's behalf. However, if the relationship sours, the SEO may point the domain to a different site, or even to a competitor's domain. If that happens, the client has paid to develop a competing site owned entirely by the SEO.

Another illicit practice is to place 'doorway' pages loaded with keywords on the client's site somewhere. The SEO promises this will make the page more relevant for more queries. This is inherently false since individual pages are rarely relevant for a wide range of keywords. More insidious, however, is that these doorway pages often contain hidden links to the SEO's other clients. Such doorway pages drain away the link popularity of a site and route it to the SEO and its other clients, which may include sites with unsavory or illegal content.

More risks to be aware of.

There are a few warning signs that you may be dealing with a rogue SEO. This is not a comprehensive list, so trust your instincts. Re-think your vendor relationship immediately if the SEO:

If you feel that you were deceived by an SEO in some way, you may want to report it. The Federal Trade Commission (FTC) handles complaints about deceptive or unfair business practices. To file a complaint, visit: http://www.ftc.gov/ and click on "File a Complaint Online," call 1-877-FTC-HELP, or write to:

Federal Trade Commission CRC-240 Washington, D.C. 20580

If your complaint is against a company in another country, please file it at http://www.econsumer.gov