This section of the forum or the
#package-development channel on the Unofficial Discord are good places to ask questions about plugin development. You can jump in with example code you might need help with, ask questions about how you might go about a particular thing, or just any questions in general.
I don't think there's an official best practices learning path, but my general recommendation would be to skim through the API documentation to get a broad sense of what you can do (no need to memorize it or anything like that) and look at the example plugins that it mentions to see how things are put together. You can use the internal
View Package File command to take a peek at any of the plugins that the API mentions.