In most established open source projects, you should find some sort of information regarding contributing to that given project. This could be called contribute.md or CONTRIBUTING.md or is simply a section in the repository's Readme file.
If you intend to contribute to a specific open source project, ensure that you follow that projects' "contribute". Most project maintainers won't accept your pull request unless you do.
For example, here's the contributing guidelines for Nightwatch -- a project I hope to cover in the near future.
https://github.com/nightwatchjs/nightwatch/blob/master/CONTRIBUTING.md
Here's a subset of their document with regards to submitting a pull request:
- Follow the usual git workflow for submitting a pull request
- fork the project
- create a new branch from master (e.g.
features/my-new-featureorissue/123-my-bugfix)
- If you're fixing a bug also create an issue if one doesn't exist yet
- If it's a new feature explain why do you think it's necessary
- ...
- ...
- Do not include changes that are not related to the issue at hand
- Follow the same coding style with regards to spaces, semicolons, variable naming etc.
- Add tests - after all this is a testing framework
