I have a few tips for you:
1) POC are not one amorphous blob. All issues are not universal across the board. Try to be as specific as possible about the race or ethnicity you're referring to when discussing the issues affecting a particular sub-section of POC.
2) If a POC crisis pops up and you feel the urge to share an anecdote here's a suggestion: don't. You're rarely offering any insight to POC and it would be much more helpful if you amplified the voices of the people who are actually being oppressed. You don't have to center things around yourself to be part of the discussion.
3) Don't join in discussions unnecessarily. If different subsets of POC are having discussions about nuances between their various groups, there's no need for you to join in unless you're directly asked for input or would like clarification.
3b) Before you ask for clarification, please attempt to Google first.
3c) Make sure you phrase your question in a way that doesn't sound like you're undermining our lived experiences.
4) It's okay to call out other white people that are fucking up. It really is. You don't need to wait for a POC to get involved before you yourself get involved.
4b) However, as much as your defense of our humanity is appreciated, if you say something that is problematic during your defense you should expect to be called out for it.
That is all.