This is a classic version, made very dry with only a drop or two of vermouth.
Ingredients:
Ice (enough to fill shaker about 3/4 full)
1 or 2 drops of dry vermouth
2 ounces gin or vodka
Olives (for garnish)
Fill a shaker with ice. Add the dry vermouth and the gin or vodka. Stir or swirl lightly, and then strain into a martini glass. (Note: Can also be served in a rocks glass filled with ice, if desired.) Garnish with the olives.