With hundreds of millions of users, Facebook is one of the prime outlets for internet advertising. This is partly because many users are regular visitors to the site and partly because it is possible to target particular types of user effectively. But the nature of the site means that some traditional tactics and guidelines for online advertising may not be effective.
One important point to remember with any Facebook ad is that the site is often seen as being a poor outlet for direct sales marketing. Those are advertisements where the idea is to directly lead the reader to buy a product or service immediately. Those companies that have been successful with Facebook marketing usually do so through relationship marketing. This is about the long-term process of getting potential customers to identify and engage with a brand, rather than a short-term one-off sale.
A big benefit of using a Facebook ad is the degree of targeting factors. Though the details sometimes vary, there are around a dozen factors that can be used to filter who sees an advert. Some of them are simple demographics such as age, gender, and location. Others are more precise, such as the university people attended or companies they work at. It's also worth remembering that these filters can be as much about making sure certain types of people don't read your adverts as about finding the right audience. Smart use of the filters can avoid wasting money advertising to people who are unlikely to be interested in what you have to sell.
People using online adverts will often try out a variety of adverts to see which get the best response. This is still a valid technique with a Facebook ad, but simply looking at how many sales they generate may not be the most accurate measurement method, particularly given that such adverts are usually displayed to a relatively low sample group. It may instead be more productive to look at the effect the ad has on the number of people who visit the advertiser's Facebook page, and then within that group how many leave comments or list themselves as a fan of the advertiser.
It's also important to make sure a Facebook ad does not inadvertently breach the company's guidelines. This can lead to an ad being ditched, or worse, the advertiser being banned from the site. Some actions that can breach the rules include ads where audio plays immediately without the user's permission, ads that incorporate Facebook's own logos or trademarks, and ads for dating sites that are not specifically restricted to adults listed as single.