Of course you must have a martini, always gin, never vodka. Most people use vermouth. If so, add just a splash of sweet–not dry–vermouth. Use the best quality gin you can afford, such Dry Fly.
2 oz gin
1-2 dashes orange bitters
Combine in shaker over ice, and strain into cocktail glass. Serve ice cold, with slivers of ice floating on top. Maybe add an olive.