Apple believes in your right to privacy. Here is some advice on how to use the privacy tools it provides on your Mac. We have a guide for iPhones and iPads here.
Use a strong passcode
To secure your Mac, all your data, and your privacy it is essential to create a strong alphanumeric login password.
The temptation to use something short or easy to remember is completely understandable, but if your Mac goes missing your life is on show, so visit Security & Privacy>General and tap Change Password to pick something more challenging.
Click here for original story, How to stay as private as possible on the Mac
Source: Computer World