How to structure a multiplayer project

I have been playing around in Unity with multiplayer for quite a while now. I am doing networking through Steam with the help of this plugin: https://assetstore.unity.com/packages/tools/integration/steamworks-heathen-s-systems-123784

My issue is not that I cannot get it to work, I can do that just fine. But always when I try I am having trouble with correctly structuring the project. By that I mean what operations to do on what end and what scripts to have on player clients and what on hosts. Right now I always come to a point where I had not been before and realize that I need to rework everything just to fix the issue.

My question is if you can help me find any great written guides and/or videos on this thematic from which I could learn more about structuring larger projects. I have checked the video tutorials on Unity networking and except some basics they dont cover advanced things that you would have in a big project.