Some guidelines I've found useful

A few things I've found useful for staying sane (well, saner than I otherwise would be) in today's world.  I can't say I've adhered to these perfectly, but when I've deviated from them, I've usually regretted it.  From the more specific to the more general:

1. Following the news will be far less stressful if you read only solution-focused items, not problem-focused ones.  If the gist of a post or article is "moan, groan, look how bad and terrible and awful this is, we're doomed", then don't bother reading it.  Read only items which focus on what is being done to solve problems, to resist and mitigate evils.  You will still be reasonably well-informed, but without wallowing in negativity.

2. You are not obligated to provide entertainment for trolls.  If somebody insists on trying to pick fights with you, delete or block or ignore him (whatever is appropriate for the type of forum or situation you're in) and go on with what you were doing.  I have dealt with several determined harassers, both on the internet and in pre-internet times.  Arguing with them doesn't make them go away.  Reasoning with them doesn't make them go away.  Publicly calling them out doesn't make them go away.  Completely ignoring them is the only thing that consistently works -- eventually.

3. On any platform that has an algorithm recommending content for you to view, be aware that it is probably suggesting things that will make you feel angry or agitated (I have particularly noticed YouTube doing this), and be prepared to actively avoid all such content, even if it looks interesting at first.  The sole purpose of the algorithm is to keep you engaged so the platform can show you more ads.  It does not care about your mental health.

4. You cannot claim to be well-informed if you read only sources of information which align with your own beliefs.  Pretty much every source has some kind of bias, and the commonest way that bias manifests itself is not distortion of the news but omission -- that is, simply not mentioning events or data which conflict with the preferred narrative.  People who read only sources that match their own belief system will often end up completely unaware of important information, and thus risk sounding like idiots when discussing what is happening.

5. Never hide your interests or feel shame about them.  Some of them may get you denounced as a snob, while others may cause you to be mocked for liking something "lowbrow", but it doesn't matter.  It's the people who share your interests that matter, and how can they find you if you don't show them?

6. Fully and guiltlessly accept whatever good fortune comes your way, no matter how unearned you may feel it to be.  You've surely had episodes of undeserved bad luck in your life too.  Think of it as balancing out.

7. Show appreciation for the positive things people contribute.  And if you haven't been doing that, then hold your tongue when they do something you don't like.

8. You learn more from listening than from talking.  People who constantly chatter about themselves end up knowing little about others, while others know everything about them.  Who has the advantage there?

9. If you live your life the way somebody else thinks you should want to live it, you won't get another life to live the way you actually did want to live it.

10. It's not true that everyone is alike deep down.  Some people really are very different from you and have completely different needs and drives.

11. Common sense and concrete results are more important than philosophical or ideological consistency.

12. One genuinely new and interesting idea is worth more than a hundred affirmations of what you already know or believe.

13. As much as possible, avoid worrying about things you can't do anything about.

14. You exist for your own sake, not to serve some abstraction like "society".

15. People can change.  But they usually don't.