Whenever I'm working with a client on their computer, or I have students in a computer lab and we even vaguely mention Facebook, I'm very vigilant on teaching them one thing: how to check their Facebook privacy settings.
Depending on when you set up your Facebook account, your privacy settings may or may not be private - if you've never done anything about it, then it's well worth spending a couple of minutes checking, and this is how.
Thankfully, the system is much simpler than it used to be, and the "average" private setting is to allow only your friends - that's the people who you approve to be friends - to see what you post. To do this, click on the little (almost hidden!) arrow at the top right of your Facebook page:
Yes, you should be able to find it with my huge big orange arrow pointing at it, right?! Once you click on that you'll get a drop down menu, so choose "Privacy Settings" from toward the bottom of the list.
Your Privacy Settings screen will look something like this:
The important part is the second half of this image - Public, Friends or Custom. You can basically ignore Custom - it doesn't offer anything that's important to many people - but I strongly recommend you switch your Privacy Setting to Friends instead of Public, if that's where it is.
During my courses, the only other tweak I strongly suggest to Privacy Settings requires a scroll a little further down the page to the second section labelled "Timeline and Tagging". This can give you the option of screening stuff (photos or updates) your friends post before it ends up on your profile page. The default options are a bit less private than what I (personally) think is OK - of course, it's up to you! But if you're interested, these are the options I choose:
And one last word or two. Whatever you put on Facebook, make sure you're theoretically OK with anyone in the world seeing it. I don't mean that you should be paranoid and complain about Facebook, but you should realistically remember that once something's "out there", it can theoretically end up anywhere - whether your friend leaves their Facebook page open at work and someone else sees it or someone forwards your status or photos to a friend - anything can happen, even though it probably won't, but just be smart about what you post online.