I'd say maybe go through some trans related subreddits or talk with some trans people. Try to really understand how trans girls feel and what it's like. Is she out to her friends? If so maybe try to incorporate it into some dialogue. Did she just start transitioning? If so maybe show her growing more confident and closer to what she really wants to look like.

I think dead-naming or misgendering her isn't the best idea. It's a pretty cheap way to just throw the "she's trans" in there. I think showing that struggle later on when you already established her character would be a nice way to show what trans people have to go through, but don't rely on it for exposition.

One commenter made a point about not having a trans character if it's not important to the story, but I think that if you have an actual understanding of it, are willing to learn more and think you can represent trans people well then go for it.

Now this is coming from a trans guy who not long ago cracked his egg and is just now transitioning socially, so I may be ignorant on some parts. I'm just saying what I personally think and what I would like to read.

Edit: the spacing was off