A good contribution
These are my simple steps on how to go ahead and make a contribution to an Open Source project in a way that might be perceived as good to the receiver.
Check out how other people are submitting their work to this project. Take a look at a few recently accepted changes and the conversation and messaging around them.
Follow that style and pattern.
If you are proposing a change or a feature, it might be worth first asking people on the project if it has a chance of being accepted. Maybe even if there are any particular guidelines or things to consider for that idea you want to implement.
When you write code, try to make a first minimal implementation and ask for feedback and confirmation that you are going in the right direction. You do not want to waste a lot of time and effort on a huge change only to learn that the project team prefer you implement it in a complete different manner.
Provide test cases and accompanying documentation for your change. Make sure your contribution can run through all the existing test cases fine.
When you have submitted your work for review and it gets tested by automated tests, make sure you hang around and respond to feedback and questions as those pop in, and updated your work to fix build failures and warnings that tools might point out to you.