the First thing a README IMO is a clear sentence (TL;DR version) what is the repo about.

After that a table of content for easy navigation.

Sections can be :

• Core Features (this to answer the question, is this project for me? is it gonna solve my problems?)
• Pre-requisites && Installation (how to install/run the project)
• Getting started (small runnable snippet of code if applicable)
• Troubleshooting (common problems and how to fix them)
• Get involved ( few nice words to encourage people and link to CONTRIBUTION.md)
• LICENSE
• CODE OF CONDUCT (really important to protect you and people)

for CONTRIBUTION.md you get some inspiration from famous repos, it's basically a spec document on how to run tests, add PR, code style and so on