Great question! You can practice speeding up or slowing down the breath just on an s sound, so no pitch at all. Then pick an interval (aka the distance between two pitches) that you’re struggling with in a song. Mimic the action you did when speeding up the breath on the s. Similarly with resonance and registers, I would pick two or three pitches you’re struggling with in a song and slowly practice aiming the sound where you want it to go. Does that help?
