Many social media sites offer options to help protect your privacy on the Web. You can make your profile private, which won't allow anyone you haven't approved to see your information, or you can remove your name from the account and use a different nickname that only friends would look for.
However, these changes will only affect your content moving forward, not the stuff you've posted in the past. So if you're just seeking a quick fix to get your personal thoughts and pictures of past and present out of the results, this is how you can do that.
First you'll need to copy the URL for your profile. Using my Twitter profile as an example, the link would look like this: https://twitter.com/c0z. Once you have the link you'll need open Google's Content Removal page -- you may need to log in to Google services again when you get there. Click the Create new removal request button and paste the link. On the next page that loads, you'll be able to remove cached content associated with the page you're having removed. In order for Google to allow this, you'll need to provide a piece of information that appears on the cached version but not the live version.
After submitting the cached information (if necessary), you will see the status page load again detailing your request along with the date. You can also cancel the request if you've changed your mind.
There's no set time on how quickly the information will be removed, so if you need your information hidden from results because you're interviewing for a new job soon, submit your request as soon as possible. Also, Google notes that not all links will be removed from search (detailed here), so you may just want to be mindful of the thoughts and pictures you share on the Web if they will impact you negatively elsewhere.
Not enough separation of social media and search engine for you? Check out Dennis O'Reilly's five ways to depersonalize Google search results.