Whatever networking site you choose to use please make sure you have a purpose. Do not use a site just because someone you know is using it. Have a reason for signing up to disclose information about you, your family or your future endeavors. If your reason for signing up for a site is to keep in touch with friends and family do just that. Get the most out of the free sites by communicating, networking with those you know and care about. If marketing yourself to potential employers is your goal then use a site like LinkedIn and be sure to keep your photos professional and personal information to a minimum.