Leave the Vermouth at the store (IMHO) - use 1 part quality olive juice and 3 parts Grey Goose (and again IMHO) there is no suitable substitute for Grey Goose it is the very finest. Shake with crushed ice and strain into a cold glass adding a dagger with 3 large olives...... for a little "flare" use jalepeno stuffed olives! Wonderful!
Nearly died from a Gin Overdose 30 years ago and I don't touch the stuff so it is Vodka Martinis only for me!