If you're about to respond to someone on Mastodon with advice or information or critique or disagreement, PLEASE read their post again to make sure that they have invited that.
If they haven't asked for input they probably don't want or need it, but if you still think they'll be interested in what you want to say, ASK before replying.
"Hey, are you asking for advice, or just venting?"
That's ALL you need to say.
I'm tagging it #netiquette (what a great word, haha) but it's universal.