I think it is important to make a distinction between your social media accounts -whether it is for personal or professional use (or both) and stick to it. If you decide to have your Facebook personal, make it private- and when people from your professional network ask to be friends, don't be afraid to politely decline and explain that it is a personal account- people are pretty understanding if you are clear and polite :.)Maybe offer up your twitter handle or whatever account that is for professional life instead.