The Facebook phenomenon continues to astound. There are close to 1-1/2 BILLION Facebook users. Facebook is the first place that most people will go to learn about a new acquaintance. AND, what is relevant to today's post, where a prospective employer is likely to look when considering a job candidate.
Hence, it is essential to pay very close attention to the kinds of things you are posting about yourself, or what you are saying in reaction to others. Put yourself in the shoes of your prospective employer and ask yourself how you would react if you were to see that post. Among the areas that require extra scrutiny: the words that you choose to use, the topics that you post about (probably best to avoid politics), and the frequency with which you post. An employer looking at your feed who sees that you've posted every day about what you think of the day's weather or what you had for breakfast is unlikely to be impressed.
If you realize that some of your previous posts are ones you'd just as soon a prospective employer not see, you can block access to them. Privacy settings allow you to select who can access your posts, so that you can limit it to friends, close friends, or custom selected friends.
Another check to perform - how much time are you spending on Facebook? The average person spends 40 minutes a day checking the Facebook feed (that's more time than is spent with their pets, and significantly more than they spend with e-mail). While this number is undoubtedly inflated by the very heavy usage of teens, the fact remains that a lot of time can be eaten up checking Facebook.
Take inventory to see how much time YOU are spending on Facebook? If you are working full time and want to advance your career, either by moving ahead in your organization or looking to move from it, many of the minutes you spend on Facebook would be more productively devoted to advancing your career, either by taking initiatives at work that separate you from your peers, by investing additional time in networking, or by more aggressively searching for new job opportunities.
I admit, I strongly favor LinkedIn as a job searching / professional networking tool, particularly for people age 30+. But lest I come across as completely anti-Facebook, let me note that the site can serve valuable career functions. One of these is liking a page that contains valuable career information. An excellent general one is "Undercover Recruiter." Some recruitment firms maintain their own Facebook pages on which they post job openings (e.g. Korn Ferry), although many of the top ones have yet to do so. Among local companies, Accenture and Marriott have particularly good job-related pages on Facebook.
Another valuable career-related Facebook function is that, with increasing frequency, people are posting job opportunities they have become aware of at their organizations. Because you are friends with the person posting these opportunities you can gather valuable information from him / her that will give you a leg up in the application process (ranging from intelligence on the organization's culture to the quirks of the person you will be reporting to). There is a also good chance that you might hear about these opportunities ahead of others, giving you more time to prepare your application.