This guest post is from Sarah Edwards, a writer and SEO at the Creare Group. You have to check out their SEO Song. It’s like marketing combined with American Bandstand.

With so many search engine optimisation companies around, it can be difficult to know which ones are protecting your best interests. It’s important to know the difference between two kinds of SEOs: So called ‘black hat’ experts, and the scammers.
First, there are the black hats.
Black Hat SEO is loosely defined as using search optimisation techniques that exploit weaknesses in search engine algorithms and go against search and webmaster guidelines (such as those provided by Google). This tends to involve excessive link building, often through spamming forums and blogs and cloaking. These tactics are risky.
But they do work. And they don’t violate any laws.
If you decide to engage in black hat tactics, just make sure you’re aware of the trade off: Black hat SEO work, but they’re a short term tactic. Once a search engine figures out you’re engaging in black hat tactics, your site will be banned. Short term gain. Long-term losses. Any black hat SEO will tell you the exact same thing.
At a minimum: If you’re a reputable business, never, ever practice black hat SEO on your primary site.
Then there are the out-and-out con artists.
Many businesses have been scammed out of thousands by such companies, who tend to promise that they can achieve exceptionally high rankings in no time at all. This is just not possible – at least not without incurring a significant cost, but some such companies can be very convincing.
So to avoid the SEOs that are effectively just con artists, it is crucial to carry out some research. Just as you wouldn’t buy a car without a test run, don’t invest in SEO or websites unless you have a clear idea of exactly what services you are being provided with. If that is black hat and you are fully aware of the risks, so be it, but do make sure you don’t let shoddy SEOs run away with your money – and your site’s credibility.