hi @Flyee welcome to the community 
I really appreciate your motivation 
and really glad you want invest time to lower entry barriers for new admins.
You will find many recurring topics looking through topics in the 
Support category. While everybody has different skills when start with Nextcloud and given the variety of installation methods this might be hard to identify generic issues.
In my eyes there are few “hot spots” mainly resulting from the lack of experience and basic IT knowledge when people start using Nextcloud following a random “setup your Nextcloud in 5 minutes” tutorial. Many underestimate how many moving parts are involved in a such software.
We already started creating “high level” articles like 101: Self-hosting information for beginners and few other articles tagged with 101 The idea is not to create another “complete the task” tutorial - many good resources exist already. the idea of the 101 series is to create a good starting point “jump start” for a specific topic like reverse proxy, DNS, TLS certificates etc. Each of the topics is complex itself but it requires at least basic understanding in all of the areas to successfully setup and maintain the application. I would really appreciate you pick up some of the missing topics from the above article and create a 101 article or review and improve existing ones.
feel free to send me a PM if you are unsure how to handle the forum and if struggle with the contents.