First - from your profile page, click on the Account tab and select Privacy Settings. At the bottom of that page you will see Customize settings. Click on that link.
Navigate down to the Places I check in to box and select Friends only. You can also select Customize and change it to Only Me. Below that box you will see Include me in "People Here Now" after I check in. Uncheck enable.
Scroll down to Things others share. You will see Friends can check me in to Places. Select Disabled.
I hope this helps.