As far as classic cocktails go, it doesn't get more classic than a martini. First appearing in cocktail guides from the late 19th century, the original recipe of a 1:1 ratio of gin (yes, that's right, gin) to dry vermouth has been been steadily increasing. It is now common to use a 4:1 or even 5:1 ratio when making a martini. Everyone has their own preferred style the drink (a la James Bond who drank a vodka martini, shaken not stirred) whether it's made with gin or vodka, served with an olive or with a twist of lemon peel, or if they like it dry (using less vermouth), or dirty (olive juice is added). Start with this recipe and tweak it to your, or your guests likings. Cheers!
Fill a cocktail shaker with ice. Add 4 ounces gin (such as Bombay Sapphire, Beefeater, Plymouth) and 1 ounce dry vermouth. Stir for 10-30 seconds and strain into a chilled martini or coupe glass, or serve on the rocks in an old fashioned glass. Garnish with an olive.