See upthread. That is not a Martini, it is just a glass of cold vodka 
What I use:
Fill glass with ice and a splash of M&R dry vermouth
stir ice and Bombay Sapphire
dump ice and vermouth out of glass
Strain gin into glass
Add three olives
drink and repeat
This is a better description of how I shake a martini. I save the aggressive of the head stuff for drinks you want to be “foamy” and whatnot.
I am finally moved to post.
From my years as a bartender, long ago:
A classic Martini is made with gin. A vodka Martini is made with… vodka.
The classic ratio of gin to vermouth is five or six to one.
Gin is best kept in the freezer along with the Martini glasses and the shaker.
As has already been established, a Martini made with some olive juice is designated “dirty.” A Martini made with a twist of lemon is a Martini with a Twist. A Martini made with cocktail onions is not a Martini. It is a Gibson.
My PERSONAL Martini recipe is both dirty and sort of with a twist. To make:
Fill shaker with ice. Take gin (usually Sapphire, but I love Hendricks, too) from the freezer; measure out 5 parts of gin and add to shaker. Take vermouth from the fridge and measure out 1 part of vermouth. Add to shaker. Add 1/2 teaspoon olive juice per Martini to shaker.
Remove glass(es) from freezer. Splash each glass twice with Angostura bitters. Add olives to pinsticks and place one stick in each glass. Swirl gin and vermouth briefly; pour equal portions into each glass. If you do it right, a tiny skiff of ice will form atop the gin mixture.
Take a broad twist of lemon peel and twist it over the top of the Martini to release the oils. Discard the peel.
ENJOY! 