There are three places that you can go to change the privacy and security settings on a Facebook account. To access the settings you need to logon to Facebook and then click the gear icon on the top right hand corner.
I suggest setting “Who can see my stuff” to Friends
Under “Who can look me up?” you could either leave it as everyone or change it to Friends of Friends or just Friends.
Timeline and Tagging
Here you can select who can post on your timeline and also who can see things posted on your timeline.
Under blocking you can add users to your block list to prevent them seeing anything to do with you account.