Microsoft has an excellent tool, the Office 365 Secure Score, to help you understand what your organization has done to reduce the risk to your data in Office 365 as well as show you what steps you can take to further reduce that risk.
The tool is available to anyone who has admin permissions for an Office 365 Business Premium or Enterprise subscription.
If you would like assistance reviewing and understanding your score, or implementing any of the recommendations from Microsoft, please contact us!