Gather your link data
Your link audit starts by gathering all your link data via Google Search Console.
You can manually export your links from Google's Search Console by navigating to the dashboard here: https://www.google.com/webmasters/tools
Click on, "Links to Your Site" under Search Traffic. Then select More under "Who Links the Most" and download the newest links as a .csv file
Once you have your file, look over the links. See any problems? Any positives?
If you found a surprising link, follow up with it. Thank the website if they spoke kindly about you and address any problem areas linking to your site.
Not sure how to search for links on Google search console?