Control who's seeing your stuff on a case-by-case basis
If you'd prefer to restrict your audience for a particular status update, photo, or video post, it's easy. Click the menu at the top of the post and you'll notice the option to select between Public, Friends, Only Me, or a custom group. And while we're at it, it's worth mentioning that if there's a particular status/photo/video/etc. you want to deploy without it posting to your timeline, select "Hide From Timeline" from its drop-down menu.
Post to a specific group of friends
If you find yourself frequently broadcasting to a particular crew (co-workers, teammates, etc.), you can create custom Friend Lists, which essentially become mini LISTSERVs. To make one, click on the Friends section on the left side of your screen (while logged in on the desktop version of the site), and click "Create List," at the top.