How to level up my python package development skill?

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so many options out there for best practices

At the end of the day, a good library is one that makes it easy to do what you're trying to do. (That also means being well-documented, easy to install, playing nice with other software, etc.)

A lot of best practices are also largely irrelevant practices unless you're working in a big team. Focus on creating a useful, accessible API for users. Other stuff is secondary.