Find something that reflects negatively on you?
Remove or delete it
Restrict access to it with privacy settings
If it was posted on someone else's site, ask them to remove it
According to a Pew Internet study, people usually comply when you ask them to take something down:
"When asked what kind of material they were trying to get removed from the internet, 76% of those who have requested such a takedown said that item was a photo or video. More than one in three (37%) said they had requested that some kind of written material, such as a comment or blog posting, be removed, and 14% said they had asked for some other kind of content to be taken down.18
The vast majority of those who have requested that some kind of information about them be taken offline say that their efforts are usually effective. Fully 82% report this..."
Source: Reputation Management and Social Media, by Mary Madden & Aron Smith, Pew Internet & American Life Project, May 26, 2012 URL: https://www.pewinternet.org/Reports/2010/Reputation-Management/Part-2/Negative-experiences-and-damage-control.aspx
Through Google Alerts you can monitor who's mentioning you and posting about you. Set up a search to run once a day or once a week on your name. When the search is executed, Google Alerts will send you an email message.