You need just two things to create great frozen margarita-style cocktails — a sense of proportion and a blender.
If you lack the latter, you're on your own. But learning the proper proportions is easy. And once you've mastered that, you'll never need another recipe.
Step 1: Start with the alcohol. Tequila is the throat burner of choice, and it often is combined with orange liqueur, such as triple sec (any liqueur can be substituted, depending on the flavor combination you're going for).
You'll need about 2 ounces of tequila per serving. Another ounce of liqueur is nice. If you'd rather skip the liqueur, increase the tequila to 21/2 ounces.
And in case you don't have a measuring cup that does fluid ounces, 2 ounces is the same as ¼ cup.
Step 2: Now consider how to flavor your drink. It's nice to balance the bite of the tequila with citrus, such as lime juice (the traditional choice), lemon juice (especially refreshing), orange juice or pineapple.
Other acidic fruits, such as pomegranate or cranberry, also are good. Nonacidic fruits (such as watermelon) are fine, too, but you may need to add a tablespoon or so of lemon or lime juice to balance the flavors.
In some cases, whole fruit can be substituted for some or all of the juice. Use your judgment here. This works well with tender berries and pineapple, but not so great with apples or lemons.