Review your Accounts
Occasionally it is a good practice to review the privacy & security settings or any suspicious activity on your accounts.
For example, it might highlight malicious third-party applications!
Screenshot by Amnesty International
You might also find devices connected to your accounts that you do not recognize, or that you have not been using in a long time. A more comprehensive list of security settings for your Google account to review can be found here. We recommend you give it a thorough read.
Facebook offers a similar security checkup at this page.