one thing that seems to be the biggest challenge for most of our transgendered sisters is the voice.
so as a former music teacher (although an instrumental band specialist i was always involved with choir as well and class voice was a breeze for me) i thought i'd add my thoughts to the challenge and suggest what has helped me.
a suggestion on the voice (that i have found works) first i talk softer (make every one else really listen!) and i shift into what's called the bottom of my "falsetto" voice. since i am a baritone or second tenor in singing voice it puts my voice into a woman’s 2nd or lower alto voice. when i first started to do this i would speak and really support the sound from down at my belly button and try to enunciate clearer since you can't force this sound as it is basically impossible.
also you will find you need to open you mouth and throat (somewhat flattening your tong in the process on the vowels) to allow the softer falsetto sound to come out and project better.
these are just good singing techniques applied to speaking (although falsetto can be hard on the voice i have been told if used for very long periods of time when forced to loudly but if supported properly and done somewhat softly i have found it to be ok and i have heard mixed thoughts on this anyway)
of course if you are a second bass as your other self and very deep in tambour this won't be all that helpful. but remember there are those gg's that really do have a deep voice and thinning hair and really are taller than 5'7" so take heart.
also i have found being over tired makes it hard to pass as i find it takes a tremendous amount of energy to go out in the public in fem because you are always on your guard for negative feedback.
just remember a smile for negative looks goes a very long way toward disarming what you think is a disapproving look. sometimes the other person is thinking about something totally different than us and is sort of looking our way but more through us than at us.
so take heart and enjoy being out in the world !