Your PR's should be nice and small, introducing one new feature to the project. For example this project would be perfect to create the addTodo function and its corresponding tests in one PR. Then you could create the markTodo in a separate PR etc. This would allow you to split the work up into manageable chunks. Coming to the project for the first time I would then be able to see a PR and know exactly the small feature you have added.
Your PR's should be nice and small, introducing one new feature to the project. For example this project would be perfect to create the addTodo function and its corresponding tests in one PR. Then you could create the markTodo in a separate PR etc. This would allow you to split the work up into manageable chunks. Coming to the project for the first time I would then be able to see a PR and know exactly the small feature you have added.