I am in my late 30's and have transitioned in the industrial/electrical field that I have been working in for almost 2 decades. I pass ok, partially because of my size and higher voice ... I work in the field for dozen's of repeat clients, usually hospitals, prisons, banks, government and military.
The issues I have experienced so far:
- Most of my coworkers and customers don't care because they don't have to deal with me, I work on my own everyday.
- The bathroom issue is easy, I'm on the road most of the time so I stop at a safe place and use the ladies room. There is only one other cis-gender woman in our office that doesn't mind me using the ladies room there.
- My coworkers don't care, so they slip all the time and call me dude, or he, or sometimes introduce me to clients as "he" or "him"
- Existing clients were surprised to see me "as the new me", some call me "she or Her", and some call me "he or sir"
- New clients are very kind and rarely miss-gender me, almost always call me by the correct name, she, her, etc...
- My employer ordered me men's shirts, not ladies shirts, even after I asked twice.
My advise in the workplace: (common sense and good advise for anyone really).
- is to always learn something new, stay up to date and be marketable, be friendly and humble.
- Smile

when a good client calls you sir (or otherwise miss genders you) and shakes you hand firmly. Wait until your not upset, and in a one and one setting to correct the client regarding your gender.
- Imagine what your company would think about you if they began to lose clients...not good...
- Don't bitch about stupid ->-bleeped-<- like the bathroom, or personal transition issues to anyone at work - ever!
- Contact your HR department with only good news, be cheerful, and know that they are not really on your side.
- If you have to contact HR with bad news or the like, make sure you email your boss and give them a chance to fix it first.
- Make sure your coworkers and management know how much you love your job, seriously!
- Smile, smile, smile, and be happy, you wanted this transition right?
- If you can, like I did, I ordered women's shirts with my own cash from the company store.
- Don't try to transition at work without an updated identification card or driver's license and Social Security Card.
Hopefully my jibber jabber above will make it's way to one's eye's or ears and I can save someone from losing their job.
((Hugs))