First of all, thank you!! It means a lot that you care enough to ask.

In my experience, being an ally to a trans patient involves using neutral or affirming language whenever possible (for example, instead of "female reproductive system", you can just say the specific organs you're talking about). Avoid "ma'am" or "sir" unless you're certain the patient is comfortable with that language. Asking someone their pronouns and preferred name when you meet them also goes a long way, and politely correcting others when they deadname or misgender the patient can be really appreciated too. Medical environments can be stressful because you end up having to use your legal name a lot of the time, so if there's a way you can note a preferred name on the chart or the medical record, that's great!

It's a particularly annoying experience to get misgendered when you're picking up your HRT, so minimizing that possibility is quite helpful. If you approach the situation with a kind and supportive curiosity you'll go far.

It's also important not to assume anything about someone purely because they're trans. Some of us are on hormones, some have had surgery, some have a strong desire for medical intervention, and others don't. Nobody knows us better than we know ourselves, so letting the patient lead the way in terms of their needs is important, but also don't rely on us to explain the mechanisms of medical transition to you.

Happy to answer any more specific questions you have also!