You can normalize preferred pronouns by declaring them when you introduce yourself. Eg. I’m Barry and my pronouns are he/him. That’s being a good ally.
If you get someone’s pronoun wrong, it’s no big deal as long as you don’t keep pushing it. They can correct you and you should just use their pronoun after. The most important thing is to use the correct pronoun once told.
You can also ask if a person you have just met has preferred pronouns.