Actions speak louder than words.

There are books out there to help you recognize patterns in people (and yourself)... It's not always easy to tell, even after knowing someone a long time.

It takes a very long time to know a person. Yet I maintain that you can’t trust anyone with everything. Jmho

Generally, it’s a good idea to look at body language. Trustworthy people tend to be comfortable making eye contact while speaking and use open and relaxed body language.

And here is another thing, they are willing to admit to their mistakes.

For me personally, I've learned the hard way so I trust very very few now.

I mean, you can't read minds so you go by pattern recognition. If you can trust them with your emotions for instance, you can discern whether you can trust them with a secret

By testing them, I guess?

Do their actions match their words?

Actions over time.

Give out that info to let it be worked on. Yeah.

there are YouTube videos by human behavior experts you might want to check out, as well as books

Mushkil he