The settings on the sites you visit allow you to choose what you share and who you share with. Understand and adjust your settings on the sites and apps you use so that you only share with those people that you want to share with. This means posts, geotagging, photo uploading, profiles, and more.
For more information about Tip 3: Know & Use Your Settings, the Online Safety Roadshow, and other great tips to help keep you and your family smart and safe online, check out: http://google.com/safetycenter