Looking fo sample schemas for reviews & DM's

Need some help creating my DB schema for reviews and DM's for Guiderhelp.com. I have a general idea of how I think it should work but would like to see how other people have implemented this functionality in their projects. I basically have guides and would like them to have reviews and dms from regular users.

Anyone know of any good resources for this kinda stuff. I am using Postgres with Hasura.

Thanks!