To save calories, this recipe uses fresh orange juice as a replacement for orange liqueur (1 ounce of Grand Marnier = 76 calories, 1 ounce of freshly squeezed orange juice = 13 calories). Personally, I don't miss the liqueur, and prefer the fresh citrus boost of orange juice, but, of course, do tinker with the orange juice ratio (or leave it out entirely) if you decide to use the liqueur along with the tequila. Also, this recipe is more tart than the standard margarita (which is my preference — not a huge fan of those syrupy-sweet bottled mixes). If you like it sweeter, try it with a 2/3-cup-sweetener to 1-cup-water ratio, or a 1-to-1 ratio if you're excluding the orange juice in favor of the liqueur (orange juice is sweeter than lime juice, so you can use less sugar). For a subtle, but interesting, twist on the classic lime margarita, substitute a portion of the lime juice with lemon juice (unrelated side note: this is also quite a yummy twist on guacamole - I always add lemon juice to my guac).