1. Add ingredients to a cocktail shaker filled with ice; shake vigorously.
2. Strain into a chilled glass.
3. Garnish with olive.
4. **Cajun Martini: substitute jalapeno-infused vodka or gin for regular gin; garnish with a pickled tomato or okra, or a tiny whole red or green chile.
5. **Dirty Martini: add 1 to 2 teaspoons olive brine.
6. **Fino Martini: substitute 2 teaspoons fino sherry for the vermouth.
7. **Gibson: garnish with a cocktail onion.
8. **Paisley Martini: reduce vermouth to 1 1/2 teaspoon; add 1 teaspoon Scotch; garnish with lemon twist.
9. **Perfect Martini: use half sweet vermouth and half dry vermouth; garnish with orange slice.
10. **Rumtini: substitute light rum for gin; garnish with lime twist.
11. **Saketini: substitute sake for the vermouth; garnish with lemon twist or olive.
12. **Scotini: substitute Scotch for the vermouth; garnish with lemon twist.
13. **Sweet Martini: substitute sweet vermouth for the dry vermouth; garnish with orange slice.
14. Tequini: substitute tequila for gin.