Learn about the bel canto style as the masters did themselves —
by reading and writing.
For your geeky self
For healthy mind/body connection
The Vaccai Method
Vaccai’s Metodo pratico de canto italiano per camera (first published in 1832) has been republished in numerous editions, keys, and languages.
Vaccai purposely limited the range of the voice in his lessons to afford the singer the opportunity to focus on the skills. You will find that you can sing the lessons in most published keys (and some others!) Sing it in whatever key/s you find most comfortable.
If you’d prefer a hard copy, any edition will do.