1. Create a strong password
Chances are, you already have your Facebook password. But you should make sure it is unique, meaning that you don’t use it anywhere else.
To change your password, go to Account Settings > General > Password. Learn more here

2. Confirm your mobile number
Doing this ensures that, even if you lose or forget your password, Facebook will be able to send you a new one via text message.
To add your mobile number, go to Account Settings > Mobile and click on Add a Phone.

3. Activate secure browsing
Another way of making sure your Facebook browsing activity is safe is to turn on Secure browsing. This automatically prevents any external applications that are integrated with Facebook from doing any harm or taking your personal information without your knowledge or approval.

To secure your account, click the drop down menu from the top right corner of your Facebook account and go to Account Settings.

Select ‘Security’ from the left menu.

At the Secure Browsing section, click on the Edit link at the right.

When the option panel appears, check the box ‘Browse Facebook on a secure connection,’ then click the Save Changes button.

4. Activate ‘Login Approvals’
Login approvals is an extended security feature offered by Facebook. It requires you to enter a security code each time you try to access your Facebook account from an unrecognised device. To activate Login Approvals, go to Account Settings > Security, look for Login Approvals and click on the Edit button.

When the option to activate Login Approvals will appear, tick the check box to activate.

When a popup window will appear with descriptions of login approvals, click on the ‘Set Up Now’ button to continue.

If your mobile number is already registered, Facebook will automatically send you a code via SMS. Enter this code in the given box and click Submit Code.

Now you have completed the Login Approvals request, so you can click Next to continue.

Next, Facebook will offer you to setup a Code Generator from your mobile phone. This would help in case you are unable to receive SMS. Click Continue.

Code generator for Android phones.

5. Disconnect previous active sessions
The good thing about Facebook is that it lets you know about your previous active sessions, where you log in from, and what devices you used to access your Facebook account. Now, to make sure your account is safe, from the Account Settings > Security page, look for ‘Active Sessions‘ and click on Edit.

Click on the link ‘End Activity‘ to kill the sessions on all other devices.

6. Activate Private Browsing
Another way to prevent another person from accessing your account is by activating ‘Private Browsing’ from your browsers. All browsers have this feature, which prevents them from logging your browsing history.

Safari
If you are using the Safari Browser on Mac, activate Private Browsing from the menu with Safari > Private Browsing.

Firefox
For Firefox, go to Tools > Start Private Browsing.

Chrome
If you are using Chrome, you can browse privately in the Incognito window. To open this window, go to File > New Incognito Window.

7. Don’t ‘Keep Me Logged In’
The moment you want to login to your Facebook account, at the Log In page, there’s a small checkbox that says Keep me logged in. Make sure this box is unchecked. Then, log in as usual. With this on, you will be asked for your email and password every time you launch Facebook.

8. Avoid clicking on links from spam email
Facebook is serious about protecting its users from spam and often enhances its features to make sure you do not become a victim. The types of attacks include requests for via Facebook messages, chat, phishing links that will redirect you to fake websites, or malicious links that could retrieve your personal information or even harm your computer. There are also chances you may receive emails that at first glance look like they’re from Facebook, are actually from a phishing website.

There are many ways you can avoid being a victim:

Never click on suspicious links.

Never give out your username or password to anyone, especially not to websites with suspicious-looking links and layouts.

Log in only from www.facebook.com and not from any other link or website.

Update your browser to its latest version to ensure your browser’s security is up to date. This will enable it detect attacks and alert you when you are navigating to a suspected phishing site.

9. Sign out after use
Lastly which is the most important of all, and definitely worth repeating, is, never forget to log out from your Facebook account.