It’s important that you are honoring your friend’s wish to use a different pronoun, and it’s normal that you sometimes make mistakes. Pronoun use is very much a habit for most of us, and changing any habit requires a little effort up front.

Here a few things you could try to help you get better at using your friend’s pronoun of choice:

1. Talk about your friend when they are not around using the pronoun they asked you to use. This will give you a chance to practice saying and hearing your friend’s name along with the right pronoun.  You might even try journaling about your friend using “they” instead of “she.”
2. Talk to your friend about why getting their pronoun right is important to you and to them. Discuss how it feels for both of you when you get the pronoun wrong.
3. Make a plan about how your friend can remind you if you say the wrong pronoun. Perhaps they could interrupt you mid-sentence to correct you, or even call you by the wrong pronoun each time you mis-pronoun them—not as a punishment, but as a way to help you rewire your pronoun reflexes.

I can tell you really want to get your friend’s pronoun right so they don’t feel hurt and so you don’t feel badly for having said the wrong thing. With a little practice, the words will come naturally!

For more information about getting pronouns right, you might want to check out the Trans* Ally Workbook by Davey Shlasko (http://thinkagaintraining.com/resources/publications/trans-ally-workbook/)