LTL,
This is a big subject and not an easy answer. However, when I started, I had a 2 octave range that started in the low base. Two years later I have lost a little on the low end but I have a 4 octave range and I am not into falsetto. I will be singing in a choir this Christmas as a soprano. My teacher started working with transgendered individuals in the mid-1970's. She has books on this and on how to rehabilitate damaged voices. She was one of the first and is the best.
1. Warm up your voice – I'll figure out how to describe this tomorrow.
2. Start to sing where you are comfortable and work up. Go up to about ½ octave lower than the top of your range.
3. As you can, extend up a note or even two and sing up to there. The key is to sing a song that goes that high but doesn't just stay that high.
4. Spend a few minutes talking every day as well in a voice that much higher than you currently speak.
5. When your voice is tired, do a cool down.
6. Start talking all day long just a little higher – a note or two. Then, as you raise your singing voice, raise you talking voice.
7. Get unbiased feedback on your speaking voice.
8. Learn how to clear your voice and how to cough without hurting your voice and to do so as a woman.
9. Repeat
Warning: Never stupid things to your voice like a public performances at outdoor weddings in October where I live. (It's literally freezing here.) I damaged my voice going to loud for too long three weeks ago and it still isn't back.
Hugs,
Jen