A. I agree with Beags as to the correct deployment of fizz.
B. However was taught this at a dinner at the Ecole Militiare at Coëtquidan:
The science of it is that you are trying to induce a stress fracture in the bottle.
Low ball nearly has it right, but is missing a key step:
1. Remove all foil from top of bottle
2. Remove wire holding cork into bottle
3. Avoid shaking the bottle in your excitment
4. Identify seam on bottle. All bottles made in 2 halves so there should be 2 seams 180 deg opposite each other. Run thumb round neck to help identify the seam.
For maximum effect (sword only):
4.a Place the bottle on a suitable table.
4.b Hold the sword so that it is on contact with the seam about 2-3 inches from the tip. Stroke up and down the seam firmly but smoothly 4-5 times from about 1/4" below the neck to about 1 1/2" below the neck. On the last stroke sharply bring the blade up to tap the neck. The induced stress will cause the cork and neck to detach from the bottle.
It may take one or 2 goes before you get it right. Best to have a practice somewhere quiet first.
This is a clear indicator of not properly stressing the bottle.
All the best
EG