How do you make a Gin Martini?

Pick your favorite Gin.   Combine One and two-thirds ounces of Gin and two-thirds dry vermouth with ice in a cocktail mixer.   Shake vigorously and strain into a martini glass.   Some folks prefer that the glass is chilled.   Often a Gin Martini will include an Olive.   If your guests prefer the martini to be "dirty", add olive brine ( juice).    Enjoy