Voice therapy can be useful - I had it back when I first tried to transition in the 1990s. It was mostly about how to make my voice sound lighter, softer and more feminine without straining or damaging my vocal chords. Fortunately I found it fairly straightforward and was able to recall it and use for this transition. I wouldn't say I sound female, I still get misgendered on the phone a fair bit but I don't really sound male either. Hope it goes well!