In the old days, you had chain letters. Nowadays, you have e-mail scams. Who hasn't gotten some spam e-mail that offered to help you make obscene amounts of money by just making a “little” investment of a few thousand pounds into this one little company? Or maybe you've gotten the more infamous “Nigerian Prince” scam, where there is a claim to have found a stash of buried treasure and of the willingness to share it, if only you will provide the money to fund the expedition necessary to retrieve it. Some of the scams are not so black-and-white, however. Therefore, it is important to know what to watch out for.
One way to avoid being scammed is to pay attention. What does this mean? Well, if the “investor” asks you to visit x website in order to see the legitimacy of the “investment”, pay close attention to the website. If it is poorly designed or has many typing errors, then you should be exceedingly leery of actually signing up for whatever is being offered. Also, pay attention to the wording of the letters. Many of these scammers try to attract people's attention by capitalizing certain words or phrases. So, if you get an e-mail of this type with words like “HUGE RETURN!” or “THE BEST WAY TO MAKE MONEY!” in bold capitals, chances are you're being scammed.
Perhaps the simplest way to avoid these scams is the application of common sense. If something seems too good to be true, then it very usually is. Or, for example, if the investment letter cautions you to not tell anyone about your “investment” until its completion, you might want to watch out. Also, try and verify the validity of their claim through some third party. Doing a search on the subject is one of the surest ways to unmask this kind of fraud.