1. The classic Martini only has 2 ingredients, so it’s particularly important to use the best you can afford – there are no fruit juices or other flavors to mask inferior potables.
 
2. Store vermouth in the refrigerator to retain its flavor longer.
 
3. Don’t chill the gin or vodka or it won’t get diluted enough by the ice to achieve the proper proportions (one-eighth to one-fourth water – it’s true!).
 
4. Energetic stirring or shaking with ice is vital for a smooth and silky result. Stirring produces a crystal-clear Martini, but it’ll never get as cold as a shaken Martini. Shaking (James Bond’s preference) creates bubbles and tiny ice shards, and therefore a "misty" appearance – which clears in about 60 seconds, so who cares? And, no, Virginia – gin cannot be "bruised."
 
5. Always serve Martinis in a frosty-cold glass (we keep ours on call in the freezer).
 
6. A classic Martini is served straight up – those who prefer it on the rocks will get a more diluted drink.

7. Garnish a Martini with a pitted olive (stuffed or not) or a 1/2-inch-wide twist of lemon peel, with which you may rub the rim of the glass. Substituting a cocktail onion transforms the Martini into a Gibson.

From The Ultimate A-to-Z Bar Guide, by Sharon Tyler Herbst and Ron Herbst.