Here are some exercices for VTO training, hope you will leave vasalva for the scubadivers...
After this step (that some cannot perform) is the sinuses flood for deep dives. BUT I DISLIKED IT..
GOOD TRAINING

Do the exercices three times per day

First week

Exercice A
Extend your tongue, jaw open, and try to touch your chin.
With your jaw open, put the tip of your tongue on the bottom of your mouth (inside lol). Try to push your tongue back and bottom.
With your jaw open, put the tip of yout tongue just behind your top incissors and try to place it the most backward possible.
With your jaw open, put the tip of yout tongue just behind your bottom incissors and try to get your tongue out of your mouth (keeping the tip behind the incissors)

Exercice B
With your mouth open, try to swallow but stop during the soft palate contraction. Control the hyoid bone goes down. This exercice is completed when you fell kind of nausea. (almost piouk)

Exercice C
With your mouth open, tip of your tongue behind the bottom incissors, push the back of your tongue back and down. Try to swallow and stop during the contraction of the soft palate.
The hyoid bone should go down.

Second week

Add to exercices A, B and C

Exercice D
Push your jaw in front, tip of your tongue behind the bottom incissors,try to swallow as previously.

Exercice E
Do exercices B, C and D with your mouth close.

Third Week
Do all exercices but insist on the B closed mouth

Fourth Week
Do all exercices but insist on the B closed mouth
5 times C, D and E
10 times B

To control efficiency
Do a small vasalva and try exercice B with your mouth close. Try to decrease the number of contractions you need to compensate your ears.

That's a translation from french so maybe it's not real american... You can ask questions....