Apologies if it was vague. Essentially, I want to 'teach' the team how to code properly so the products in production don't keep breaking. A standard way of coding such that later, we can audit/review the codebase based on.

I am looking for a 'software quality assurance checklist' but whatever I have found on the web, is too general/not related to actual coding best practices.

Example: some people use OOP without returning anything in a method, some people use OOP but treat a method as a function that takes inputs and outputs.

I know this is general, but how do you enforce a single style of coding to people? how do you audit a piece of code? based on what?