Ernest Hemmingway, an expert in these things, preferred a ratio of 15 to 1 Gin to Vermouth, and called it a Monty, after the British General Montgommery, because he would not attack unless he outnumbered the enemy by this ratio. I like to fill a shaker with ice, pour in a small amount of vermouth, shake to coat the ice, pour off any free vermouth, add the gin, stir briefly and pour into chilled glasses. A lemon twist is all that is needed, perhaps some home made salted crisps.