I used to be a tenor until a couple months ago. I have heard it mentioned time and again that the vocal range for pitch and resonance does not increase in frequency during feminization, but for me it did.
I plan on posting some unlisted youtube videos of myself singing accapella (because audible music will flag for copyright).
Previously my vocal range ran from baritone to alto, but I could only really "project" my voice in tenor range.
Although I could sing alto previously without usage of falsetto, my old voice always sounded more like Micheal Jackson (using vocal register) or prince (falsetto) and less like Blondie or Nancy Sinatra. Now I can push my resonance beyond that of Blondie's alto, believe or not!
Avoid falsetto if possible. You'll come off like Monty Python style drag comedy at best, or cartoonish like muppets. Falsetto quartets used to be a fad in the 60s. I'm glad it died off. Before my time but it sounded awful.
I still present as male full time but speaking for extended periods in my old tenor resting voice is painful. It's at he bottom of my vocal range now and sounds like I have a sore throat when I try to talk low.
Bass/baritone i can do no more. Tenor sounds forced, almost like a cis-gendered woman trying to act macho. My alto range is mature but doesn't project like my old tenor voice. If I attempt to shout, pitch drops oddly enough.
Though my speaking voice is fairly androgynous sounding, I have found singing a verse or so of any alto female pop song temporarily pushes my range up. Humming sofly if you are in mixed company or don't know the words is just as effective.
Because I am feminizing using street legal otc health supplements (dhea) instead of a proper metered dosage from prescription hormones, my resting vocal range will rise and fall based on the ebb and flow of the unregulated levels in my body.
I cannot project in alto like I used to with my tenor voice. Doing so or forcing it too high or too loud too soon can cause damage. I suffered a bad case of laryngitis a few weeks ago that took several days to recover from. Remember, your vocal cords are underdeveloped during transition like a school girl, but you have the lung capacity of an adult male. If you feel pain, cease singing and rest your voice immediately.
Try Sade for starters. She's gentle and effiminate that many cis- or non-transitioning tenors can emulate her. Blondie and Joan Jett are more good artists to emulate when you get practice. Cindi Lauper Girls just wanna have fun or Madonna if you are more advanced. Frequent stretching will help effeminate your voice, but please don't overdo it to the point of injury.
Simple rap lyrics like Fresh Prince of Bel Air are good for gender bender training your voice. If you can learn to control pitch and resonance separately, you can emulate just about anyone within range.
My church doesn't know I'm trans yet but pastor has been begging my fiance and I to join the praise team for months. His hope is that if I join the choir, it will encourage other "men" to join. I will be the only "man" up there, and if I join, I'll be singing in alto because I literally can't do tenor anymore. I can't pass up a golden opportunity like this one.
This could potentially get weird in a few months when my breast growth becomes to obvious to hide from the congregation anymore...