For a classic salted rim, use kosher salt. For more kick and tang, use Tajin (chile-lime seasoning). You can also take a margarita to a sweeter side by rimming the glass with coarse sugar or even cinnamon sugar.
A margarita is traditionally made with tequila, but tequila skeptics can substitute vodka. For a layer of smokiness, substitute 3/4 ounce of the tequila with an equal measure of mezcal.
If you like, before adding ice to the shaker, drop in a few chunks of fruit (strawberries, raspberries, blackberries, peach, mango or pineapple), a slice or two of fresh jalapeño or ginger, and/or an herb sprig (cilantro, mint, thyme or rosemary). Add spirits and lime juice and muddle well. Taste for sweetness, then add the ice and shake.
For a slushy drink, combine ingredients in a blender rather than a shaker. With machine running, gradually add 3/4 to 1 cup ice cubes and/or frozen fruit, such as cubed watermelon, pineapple, or mango.