This is going to be an extremely short post, and I will share a tip that changed my life.
The Tip: treat testing code as you treat your production code.
It means linting, PR's, and following code conventions.
It sounds basic, but testing code quality is used to be neglected under pressure, but since it's our safety net for bugs in production, we should give it respect and take care of it.
Clean test infrastructure means more quality tests.