Well, of course everybody has their own magic incantation that
they think is the One True Method. But mine is the right one.

I mostly use Boodles gin, but my second choices are Bombay
Sapphire or Beefeater. I use Noilly Prat dry vermouth, but I
doubt that matters too much.

In a shaker, I add 7 ice cubes. These are 3/4 ounce cubes, so
5.25 ounces of ice. Less ice makes the drink watery and more
makes it too strong. If your ice cubes are different sizes,
you may have to experiment. My mom's and your mom's ice cubes
are different sizes from mine at home, so I eyeball it, which
means it's not *that* crucial -- but try!

After the ice is in the shaker, add 1/2 ounce of vermouth and
2.5 ounces of gin. This is a 5-to-1 ratio. Others may quibble
with my choice. They are wrong.

Shake or stir. No, it really doesn't matter to me. I shake,
except when I make 5 at a time in a big pitcher, I stir. But
if you shake don't shake so hard that it gets bubbly. Shake
until it's really cold. I use a metal shaker and shake until
the cold hurts my fingers. At least 30 seconds.

Scale up as needed, even (especially) the ice. For five
martinis, do you *really* need 35 ice cubes? Yes! Generally
the liquid should not cover the ice when first poured in.

Strain into a cocktail glass with olives.

Mmmmmm, have one for me.