Just before serving, in a half gallon pitcher combine the tequila, the minimum amount of Cointreau or Triple Sec and the lime juice. Taste and add more orange liqueur if you think your margaritas need more sweet oranginess to balance the other flavors. Remember, you're tasting it warm and undiluted; when chilled and diluted, the flavors will be mellower and the lime's tartness will be more attractive.
Pour several tablespoons of lime juice onto a small plate and several tablespoons coarse salt onto another. Have martini glasses at hand (chill them for an extra special touch).
As your guests ask for their margaritas, invert a glass into the plate with the lime juice to moisten rim, then lightly dip into the plate with the salt. For each drink measure 2 ounces (1/4 cup) of the margarita mixture into a cocktail shaker. If you have a 2-ounce ladle that you can keep in the pitcher, measuring goes much faster. Add ice cubes (5 cubes for 1, 8 for 2, 10 for 3). Secure the lid and top and shake vigorously for 10 to 15 seconds. Strain into the salt crusted glasses and hand off to the lucky recipients