It's not five things, but some general DevRel advice I've learned over the years:
make sure the sample code (or whatever) to use your platform is well-written and polished—99% of devs will copy and paste it to create their experience
be your zeroth customer—constantly ensure your onboarding experience works well and try to look at it from different levels of experience
what 'community' means is different to everyone (mailing list, public chat, GitHub issues... ?), but make sure you have one, and code samples/answers are well-indexed so when folks search, they can get their answers easily!
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