Be charitable. Assume the people you're talking to or about have thought through the issues you're discussing, and try to represent their views in a way they would recognize.
When making a claim that isn't outright obvious, you should proactively provide evidence in proportion to how partisan and inflammatory your claim might be.
What is a strongly held opinion you once had that has been changed due to the rationalist community? (self.slatestarcodex)
I’ll start off by saying I used to be a big believer in the hype surrounding “growth mindset.” After doing more research and reading some SSC pieces I no longer hold the same strong opinion about it. I was wondering if anyone else has some good examples?
Surprisingly enough, it probably convinced me that civil good-faith debate and conceptual thinking inside rigorous systems are much less useful than I had assumed. Not to say I think it's useless; But I now think of it as a very useful tool among many others. A tool that not many people have and that I can take advantage of. But not a magic method that is required to accomplish anything of value.
It also helped me lower my priors on most things I thought I knew. I saw the shakiness of ideas/information I thought solidly grounded. This did not result in a significant update. However, I've been able to change minor beliefs more quickly, which after 2 years reflects as major life changes. Plus it's made me a bit less stuck up (both behaviorally and phenomenologically).