Set your privacy settings to the highest level. You might think you're only posting to friends, but search engines can see loads of Facebook information unless you have your privacy settings cranked up. Google yourself regularly to see what information is publicly searchable on your Facebook pages. Assume your coworkers, supervisors and potential employers will do the same.
By default, friends, likes, groups, hometown and current city, relationship information, gender, networks, and work and educational history will show up, as will your wall postings. Moreover, some information -- including your name, profile picture, gender and networks -- will always be visible to outsiders, no matter how high you set your privacy settings. According to Facebook, others must have access to this information so that they can locate, identify and connect with you.
Facebook does not currently grant third party applications or ad networks the right to use your name or picture in ads, but nothing prevents the company from engaging in this practice in the future. If you don't want this to happen, adjust your account settings accordingly.