Asklemmy

First off, thanks for asking and wanting to be more inclusive! :)

For your pronouns, you decide. If you typically go by "he/him" you can keep doing that, it's up to you.

Depending on the setting, people around you might all introduce themselves with their prefered pronouns, you can introduce yourself with your pronouns if you wish to whenever though.

Similar to how you might tell people a different name you prefer to go by. So if your given name was Nicholas but you prefere to go by "Nick," you might introduce yourself like, "Nice to meet you, I'm Nicholas, but just call me Nick." likewise, you can say something like, "Nice to meet you, I'm Nick, He/Him"

Online, it's fairly common now to have your pronouns in your profile or bio. Again, it's up to you if you want to put them in your bio or not. Some sites have actual places in the sign up screen or profile page to place your pronouns, it depends on the site/software.

It's rare for people to get offended IRL if you unintentionally mis-gender them. Most people will correct you politely in the same way they might if you called them by an incorrect name. So if you said, "Hey Nicholas, how are your classes going this semester?" they might say, "Oh, you can just call me Nick. Classes are going well so far, how about yours?"

Often people that know them will correct you politely too if you don't know and used the wrong pronouns. I've had it happen a few times over the years and everybody has always been very polite about it. I just quickly say, "oh sorry, my bad." and then just make sure to remember their pronouns going forward.

I personally have some family and friends that use they/them vs she/her or he/him. It's a thing for sure, we all support them and their pronouns. It's not very tough to get used to, and as long as you correct yourself if you make a mistake, nobody will be hurt. It's fundamentally about loving them and being inclusive and supportive.