Open source is undoubtedly changing the software world we live in today. People building applications, frameworks, modules, and all kinds of of other software things are able to feed off of one another's design and style ideas. There are a slew of online code collaboration websites that make writing programs with others easier than it has ever been before.
The advantages that open source software brings to life also bring new challenges in etiquette and adaptation. When contributing to an external open-source project, it is important to keep an open mind and consider the use case.
When contributing to an open source project, it is important to put your own personal preferences and style practices aside. If the program you are contributing to uses tabs for indentation, use tabs. If the comments are all written in C-style, double-slashed, or block quotes, write yours the same way. If the code follows some particular style guideline, adhere to it. If you don't, you are forcing the maintainter(s) to choose between accepting inconsistency in their project, asking you to change your code, ignoring you, or flat out rejecting your contribution. Keep in mind that it is easiest to ignore, so shape your code properly before asking for a merge to maximize your chances of being accepted.
Use what they are using
There are so many ways to solve the same problem in software, which makes it very easy to import multiple libraries that accomplish the same task, perhaps without knowing you are doing so. Take the time to familiarize yourself with the project. What functions or modules does it use for mathematics? String comparison and manipulation? Date and time formatting? Using multiple libraries to accomplish the same task based on developer preference is an anti-pattern that we should all try to avoid.
Be thorough during code submission
As a software developer, you will have your own opinions on what would work better, or how a project could be more effecient, and that's a good thing. If you feel that one of your ideas is beneficial to the project in reasonable balance with any negative impact to productivity or uncertainty, suggest it to the maintainer(s) using the appropriate channels. It's usually better if some conversation around your feature has been had prior to our submission, but often times as developers we write the code first to see if it will work, then get excited about it and want to share. Just make sure you convey your use cases and reasoning clearly to give others the full context of why you thought the change was a good idea.
Think about what it would take for you to merge someone's changes into your favorite original project and apply it to the way you go about making outbound contributions. After all, the objective of open source software is to solve a problem, not to have one hundred slightly varied versions of the same software because nobody could agree on anything and forked their own.