Passwords and Multi Factor Authentication
By its nature, Cloud Services are always online and reachable. This makes cloud services the perfect target for hackers to attempt to breach your Security.
Enforce stonger password rules when moving to the cloud.
Enfore longer, complex passwords to your users. Train them on using passphrases in stead of simple passwords
Enforce the use of Multi Factor Authentication
Most Cloud providers offer Multi-Factor Authentication via an Authenticator App. Train your users on the usage of MFA, and enforce it for all services in the cloud.