The most important shift is to stop thinking of penises, testes, and prostates as "male genitalia" and to stop thinking of vulvas, uteri, ovaries and clitorises as "female genitalia". If you can unlearn this thinking, everything else will follow easily. 

For people that have grown up in a culture where gendered language has always been used as a short-hand for genitals, the thought of using anything else can seem confusing, or even scary.

Sex negativity is so prevalent that many people are genuinely ashamed to say the words "penis" or "vulva". Not only will it benefit transgender and intersex people to unlearn this shame: it benefits cisgender people to unlearn this shame too, as it promotes body positivity and bodily acceptance.

When talking about people's bodies, the most important thing for any medical provider to do is to use the language that the client prefers to use for their own body. Especially when talking to the client or talking about the client's body.

Some people are okay with medically accurate terms, or even bioessentialist language. Others use existing genital language to re-name their body parts. 

A trans women may call her genitals a 'clit' or a 'pussy' and a trans men may call his genitals a 'dick'. Intersex people may also use terms like this. Practice using this language when relevant.

When writing about transgender and intersex people in articles, textbooks, literature, or academic papers: the best practice is to use medically accurate terms.

Never use "biologically male" or "male bodied" to refer to transgender women, non-binary people, or intersex people who have a penis, scrotum and/or prostate. Instead you can say:

-Transgender women
-Transfeminine people
-Intersex people
-Non-binary people
-People who have a penis
-People who have a scrotum/testes
-People who have a prostate

Never use "biologically female" or "female bodied" to refer to transgender men, non-binary people or intersex people who have a vagina, uterus, ovaries and/or clitoris. Instead, you can say:

-Transgender men
-Transmasculine people
-Intersex people
-Non-binary people
-People who have a vulva
-People who have a uterus
-People who have ovaries
-People who have a clitoris

As you can imagine, referring to people's genitals only has specific use cases. Talking about people who have prostates, is only relevant when discussing the medical risks associated with that specific body part. Talking about people who have a uterus, is mostly associated with the risks of pregnancy. If you aren't discussing those situations, you don't need to mention them!

As a counselor who may engage with research, teach, or write textbooks, it's also important to remember that not all transgender women have a penis, and not all transgender men have a vulva. Intersex people can have a multitude of configurations for their bodies. When talking about the specific medical discrimination that gender-diverse people experience it's helpful to use language that avoids making assumptions. For example:

"Some transgender men face medical discrimination if they need birth control."
"Women who have a prostate may have difficulty accessing prostate care."

Traditionally many transgender and intersex people have been called "male to female" or "MTF" and "female to male" or "FTM". Many transgender and intersex people now see these terms as a workaround for implying what genitals they have. As such, it's usually best to avoid these.

The same can be said for "Assigned male at birth" and "assigned female at birth" AMAB and AFAB respectively. Many transgender and intersex people do not want to be forever identified based on cisgendered people have misunderstood them.

Many transgender and intersex clients still use the terms AMAB, AFAB, FTM and MTF to refer to themselves. As always: the most important thing is to refer to people with the language they are asking you to use.